Add an engine property to the generated templates.

[3rd-Eden]

This is issue is related to the work that we've been doing on integrating react together with other templates engines. The biggest difference between react's setup is that requires DOM nodes to be returned an passed in to template. There are use cases that we want to know which engine a certain template runs so we can decide how we should handle the returned contents.

What i'm wanting to introduce is a new engine property on the returned templates. So we can inspect it and decide on how we want to handle these templates.