current latest sbt version for 0.12 is 0.12.3
better error message if illegal sbt version is supplied
fix #22: also force update when publish-local

Otherwise, generated ivy.xml can contain wrong versions from previous
builds for other sbt target versions.
whitespace
backport CrossVersion support to 0.11.x as a preliminary of #21
enable cross building for sbt 0.13.x, fixes #21 (`scripted` still broken)
use scripted runner from 0.13.0-RC3 in all versions, fixes #14

Necessary changes:
  * fix scripted-sbt version
  * adapt reflective calls to latest ScriptedTest signature
  * fix scala version to use to run scripted-sbt and provide proper scalaInstance
allow supplying of `scriptedLaunchOpts`, fixes #16
Merge branch 'sbt-0.13-support'
bump version
adhere to best practices and require manual inclusion of crossBuildingSettings to enable plugin
(cherry picked from commit b39e1709f2c711028981818e9519263c5ca77255)
remove broken tests to test scripted for now
fix scripted launcher, refs #16
bump version to 0.8.0-RC1
Merge branch 'master' of github.com:jrudolph/sbt-cross-building