Upgraded to Netty 3.9.2

Netty 3.9.2 contains a DoS vulnerability fix in the SSLHandler.
Document the removal of implicit parameters

Fixes #2799

Documented the removal of the session, flash and lang implicit
parameters in the migration guide.
Deduplicate assets

Fixes #2936

If two modules depend on the same webjar, there will be duplicate
mappings to the assets in that webjar.  This commit fixes that by just
taking the first.
Anorm column parser for JDBC Array
updated example of using ``play`` with ``grunt``
Update SBTCookbook.md
Merge pull request #3068 from ivpusic/patch-1

updated example of using ``play`` with ``grunt``
Fix spelling of default in SBTCookbook
Merge pull request #3070 from gmethvin/default

Fix spelling of default in SBTCookbook
Merge pull request #3066 from jroper/netty-3.9.2

Upgraded to Netty 3.9.2
Documentation for thread locals and thread context class loaders
Merge pull request #2799 from jroper/2799-document-session-flash-removal

Document removal of session and flash implicit conversions
Merge pull request #2936 from jroper/2936-deduplicate-assets

[2.3] ZipException: duplicate entry while doing sbt 'dist'
Merge pull request #3071 from richdougherty/iteratee-thread-pool-doc2

Documentation for thread locals and thread context class loaders
Upgrade to Twirl 1.0.2
Merge pull request #3072 from benmccann/twirl102-take2

Upgrade to Twirl 1.0.2
Upgraded to js-engine 1.0.1
Merge pull request #3062 from cchantep/anorm-array

Anorm column parser for JDBC Array
Merge pull request #3069 from jroper/js-engine-1.0.1

web-assets:assets Duplicate mappings on runtime
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