Version 1.2.4.
Choose crossVersion style based on isSnapshot (thanks to Nikolas Evangelopoulos).

Conflicts:
	CONTRIBUTORS
Set scalaVersion to 2.10.2.
Bumped SBT and plugin versions.
Added Travis configuration.
Merge branch 'shapeless-1.2.4' into shapeless-1.2.4-scala-2.9.x

Conflicts:
	project/Build.scala