Merge pull request #4 from gkossakowski/play

Add Play2-core
use slick PR from Eugene; run continuations tests
typo in ref
Try to workaround problem in continuations build
Back to sbt/sbt#0.13, and add scala-async
use correct git uri
Disable async tests for now, use patched SBT
Fix git ref; remove obsolete workaround
Switch back to tracking sbt's 0.13 branch.
Merge remote-tracking branch 'retronym/jenkins' into spray
Build the whole Play2-core again.

For spray we needed just Play-Json but now that we are preparing for
merging upstream, let's build entire Play2-core.