build: Upgrade to scala 2.10.
build: Update to sbt 0.12.2.
build: Add org.scala-sbt organisation.
Rename Version to Main, & move to sbt.dynver package.
Add SemVer, with 2 implicit classes in the root package object.
build: Add specs2 v1.13.
test/SemVerSpec: Add spec for SemVer.