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.
This is probably my ignorance of how this file is run by Jenkins but I'm not sure what this sentence means. Does it mean that Jenkins checks out a tag of the repo and so the initial state of it has no branch?