Initial move to using twirl for template parsing.

## Review, but do not merge!

Initial work for moving off of Play dependencies and using twirl instead. Twirl is cross-compiled and will allow us to move freely on different Scala versions independent of Play.

Still failing tests for 2.11, help is appreciated to push it to completion.
There's probably some encoding we should pass around (current code preserves the original, that relied on the default encoding as well).