Made routes compiler its own plugin

* Improved the structure of routes compilation, so that it's more
  configurable
* Made the incremental compilation good
* Took many of the old integration tests for the router and turned it
  into a scripted test
* Wrote scripted tests for incremental compilation
* Included mocha tests for the JavaScript reverse router in incremental
  compilation
Remove duplicate documentation test

I accidentally added a duplicate test when cutting and
pasting from another test in #3701.
Merge pull request #3067 from jroper/routes-compiler-plugin

Made routes compiler its own plugin
Fixed double slash in fingerprinting

Also added tests for the reverse router for fingerprinting.
Issue #3082 (show imports for ScalaTest samples) and issue #3083 (improvements to ScalaForms)
Merge pull request #3086 from kipsigman/docs-forms-scalatest

Docs: ScalaTest and ScalaForms improvements
Merge pull request #3084 from richdougherty/remove-doctest-cruft

Remove duplicate documentation test
Merge pull request #3074 from jroper/fingerprint-failure

Asset fingerprinting produces URLs with a double /
Added info about which version of Play the templates are being published for

Also made the build script a little more robust
Added Play version numbers into the tutorial