Bump to 1.6.1 and use version from submodule

Use the version from the submodule for the gem version. So it is
consistent with other types of toolkit packages.

Change the jenins.sh to update the version of the submodule as part of jenkins.sh and commit the updated submodule after the gem has been published. I can then update jenkins to push the master branch as a post build step.
Sorry that possibly wasn't very clear. When jenkins runs it does the equivalent of `git checkout [commit-sha]` where the commit-sha is the most recent commit on master. This means by default it is on a detached tree or not on any branch.