Scala 2.9/2.10 language & library support

Here's the scala language & library support. It has a sub-module for each scala version (they're not binary-compatible) - I've done it for 2.9 and 2.10, as I know some projects still haven't built for 2.10, so many people are still forced to use 2.9.

Where possible, I've shared code between the two versions, which is in betamax-scala/src, and is included in the source sets for the sub-modules, via the common gradle script, gradle/scalaModule.gradle

I wasn't sure how rigorous to go with the tests - strictly speaking I should have tests that use the tape mode and match rules arguments, but I didn't have time to add them yet.

Hopefully @rslifka might have a chance to look at what I've done.