[JCLOUDS-702] JCloud ProfitBricks provider implementation

Hi! This implements most of ProfitBrick's API. I look forward for your comments, suggestions, and revisions.
Minor: there's no need to manually format the message. The [checkNotNull(T,String,Object...)](http://docs.guava-libraries.googlecode.com/git-history/release/javadoc/com/google/common/base/Preconditions.html#checkNotNull(T,%20java.lang.String,%20java.lang.Object...)) method already does that.