* The base Aspect class is added and is an idempotent propagating visitor, that
 recurses during the visit action
 * The first aspects are for tags
 * TagManager has been re-implemented to only handle setting removing
 and formatting tags
 * Tags can be included or excluded based on Resource Type, this
 replaces the the need for all previous tag properties
 * VPC, Security Group, KMS Keys, and AutoScaling are updated to use tags
 * Tag Aspects overwrite tags passed into the L1 during initialization

…are involved

… changes from code review

… on the aspect

Aspect framework is added. Aspects can be used to affect the construct tree without
modifying the class hierarchy.

Tagging has been reimplemented to leverage the Aspect framework and simplify the original
tag design. Tag Manager still exists, but is no longer intended for use by L2
construct authors. There are two new classes `cdk.Tag` and `cdk.RemoveTag`.

Code generation has been modified to add tag support to any CloudFormation Resource that
supports tagging, by creating a Tag Manager for that resource as a `tags` attribute.

Breaking Change: if you are using TagManager the API for this object has completely changed.
You should no longer use TagManager directly, but instead replace this with Tag Aspects.
`cdk.Tag` has been renamed to `cdk.CfnTag` to enable `cdk.Tag` to be the Tag Aspect.

Fixes aws#1136.

EC2 task definitions can now be used as CloudWatch event targets.

ALSO IN THIS COMMIT

* Improve hash calculation of Docker images.
* Add `grantPassRole()` method to iam.Role

Fixes aws#1370.

Add source map support to the TypeScript app entry point template.
This won't retroactively fix existing CDK apps, but it will ensure
that apps generated in the future via `cdk init --app` will have
it enabled.

Fixes aws#1579

The property was modeled in the wrong place, rendering it unusable.
Moved it to the correct location instead, and added a validation test.

Fixes aws#1608

Constructs can now take a dependency on any other construct.

Before, only `Resource`s could take dependencies, and they would depend
on `IDependable` which had to be implemented explicitly. In this change
we generalize the concept of dependencies from construct trees to other
construct trees; all constructs now take dependencies and also implement
`IDependable`.  The semantics are that any resource in the depending
tree will depend on all resources in the depended tree.

Dependencies are cross-stack aware

If you take a dependency on a construct in another stack, the dependency
does not get rendered in the template, but is instead added as a
dependency between stacks.

Fixes aws#1568, fixes aws#95.

BREAKING CHANGE: `resource.addDependency()` has been moved onto
`ConstructNode`. You now write `resource.node.addDependency()`. VPC's
`internetDependency` has been moved to the subnets as
`internetConnectivityEstablished`. Target Group's
`loadBalancerAssociationDependencies` has been renamed to
`loadBalancerAttached`.

See CHANGELOG

Adds `LambdaApplication` and `LambdaDeploymentGroup` such that an `Alias` to a Lambda `Function` can be deployed via CodeDeploy; supports pre/post hook functions, traffic-shifting and alarm monitoring and rollback.

…#1664)

Adds option to enable all block public access settings on the bucket (`blockPublicAccess`). Also throws an error when trying to use grantPublicAccess if blockPublicAccess is set to true.

https://docs.aws.amazon.com/AmazonS3/latest/dev/access-control-block-public-access.html

…ource Type

A generalized aspect framework is added. Aspects can be used to affect the construct tree without modifying the class hierarchy. This framework is designed to be generic for future use cases. Tagging is the first implementation.

Tagging has been reimplemented to leverage the aspect framework and simplify the original tag design. Tag Manager still exists, but is no longer intended for use by L2 construct authors. There are two new classes `cdk.Tag` and `cdk.RemoveTag`. As new resources are added tag support will be automatic as long as they implement one of the existing tag specifications. All L2 constructs have removed the TagManager.

Code generation has been modified to add tag support to any CloudFormation Resource with a matching specification, by creating a Tag Manager for that resource as a `tags` attribute. The schema code now includes the ability to detect 3 forms of tags which include the current CloudFormation Resources.

BREAKING CHANGE: if you are using TagManager the API for this object has completely changed. You should no longer use TagManager directly, but instead replace this with Tag Aspects. `cdk.Tag` has been renamed to `cdk.CfnTag` to enable `cdk.Tag` to be the Tag Aspect.

Fixes aws#1136.