prepare for version 0.5
update plugin dependency to use latest
start to add spec for RvmWrapper
update .gitignore
add jenkins.rb rake tasks
add .travis.yml
add script to convert class name in config.xml

This is because of updating jenkins-plugin-runtime from 0.1.17 to 0.2.3.
This script also fixes JENKINS-18841.
change the default implementation to '.'

'.' means read project rvmrc (or other files). See comments in #4.
Merge pull request #13 from eitoball/release_version_0_5

Release version 0.5