Fix for redhat clone with yum rpm, same strategy as the debian with apt-get and .deb file.
When the rpm repo is used an old 0.11 version is used that cannot update/upgrade to the latest 0.12 releases.
Now the rpm is downloaded and installed from http://scalasbt.artifactoryonline.com/scalasbt/sbt-native-packages/org/scala-sbt/sbt/ as default
fix for override default values
chef.json in Vagrantfile"
:scala_sbt => {
  :repo_url => {
    :redhat => 'http://scalasbt.artifactoryonline.com/scalasbt/sbt-native-packages/org/scala-sbt/sbt/0.13.0/sbt.rpm'
  }
}
Merge pull request #3 from everestnl/master

Fix for sbt 0.12+ on centos with yum rpm's