Fix for Issues #5, #8

* Check to see if a dependency is a project dependency before we add it to the list of snapshot dependencies.  Project dependencies should be excluded, because they will be snapshots until the release is complete.
* Added some finer-grained control over the release tag that is created.  We can now optionally exclude the source branch from the beginning of the tag. (With README changes)
* Cleaned up inconsistent tag regexes.  The Plugin proper was using the word "RELEASE", but the regexes in the SCMService implementations were using the word "REL".  They are now all using "RELEASE"
* Added a boolean flag to the configuration that allows the user to have the local workspace switched to the tag after the tag has been created.  This will ensure that the release build is run from the tag itself, and not from the source branch which incidentally matches the tag. (With README changes)