Pom cleanup

fixing dependencies, extracting property values, updating scm, setting
jdk target.
Update to new atlassian maven repo
Cleaning up create new version mojo

Still not sure about doExecute signature and is it enough.
Refactoring the AbstractMojo to work with REST
Refactored ReleaseNotesMojo to work with REST
Updated Release Mojo to work with REST
Taken out tests which will need to be added later