sbt 0.13 support

[kulikov]

What do you think about sbt 0.13 support? Do you have some plan on this?

[ryan-williams]

+1!

[hoffrocket]

Anyone want to help? I've made an attempt, but my kung-fu is not strong enough for sbt. Got stuck with plugin: https://github.com/foursquare/spindle/tree/jon-sbt