Don't try to load untyped classes (e.g. anonymous functions) as DDL

This fixes reflection errors that occur when upgrading to Play
2.3.0-RC2. This fix should be safe to use for previous versions of
Play too.
upgrade to slick 2.0.1 and play 2.3.0-RC1
Upgrade to Play 2.3.0-RC2, Slick 2.0.2, Scala 2.10.4 and sbt 0.13.5-RC3

* Change samples' Build.scala files into Play 2.3 style build.sbt
  files.
* Root project doesn't need reference to Play plugin
* Use a trick to hide Specification's implicit ExecutionContext
Update plugin version information in readme