Added AutoPlugin, heavy refactoring
Added more tests for scalastyle:test
Added cache file, restored scalastyleConfigUrl
Added more tests for url
Updated descriptions of settings & tasks
Make package correct
Update sbt version to 0.13.6

Including this plugin in an auto-plugin somehow causes projects that include that plugin to load the older 0.13.0 sbt library, instead of the more current one configured in the plugin. This causes a compile-time error under some circumstances (see https://github.com/sbt/sbt/issues/1592). Building this plugin with 0.13.6 should solve the problem for the time being for plugins including it.
Merge pull request #30 from jastice/patch-1

Update sbt version to 0.13.6
Merge branch 'master' of github.com:scalastyle/scalastyle-sbt-plugin
Removed extra stuff from build.sbt
Release 0.6.0
Added signing
Prepare for next iteration