Feature Enhancements with tags and url support

added the ability to add tags to a stack
provide example in readme on syntax for adding tags
added the ability to use url for template json file that is outside amazonaws domain

Thanks to @myappleguy for his pull-request.

Multiple Exit Codes

This release enables multiple codes based on status, for example if no updates are required, it will return 2 instead of a generic one which can be used in build to go green.

Maintainence Release

v0.0.13

Dockerizing project.