Change API for registering dependencies with Cake

[patriksvensson]

Currently there is some problems with ICakeContainerRegistry and ICakeRegistrationBuilder.

• Methods in both are generic, which makes it cumbersome to register types. This can be solved by changing methods to accept Type and add extension methods on top.
• ICakeContainerRegistry should be called ICakeContainerRegistrar since it's something that registers things with a container and not a registry over containers.
• The ICakeContainerRegistry.RegisterModule is out of place and should be removed. Could be added as an extension method.