Release version 0.5

I would like to merge following changes to master to release version 0.5.

* update plugin dependency (ruby-runtime: 0.7 to 0.12, token-macro: 1.5.1 to 1.9)
* make the default implementation to '.' based on discussions in #4
* provide script to change class name in config.xml caused by updating ruby-runtime
 * also fixes JENKINS-18841
* start adding spec for `RvmWrapper`

@hsbt please review