Add option to bump minor rather than patch by default in GitVersion

[JakeGinnivan]

At some points in the project (at the start) you may want to just bump minor by default because you will likely be releasing a minor next. If you need to release a patch we can borrow the support branch idea from GitFlow, then release the bugfix from the support branch

[JakeGinnivan]

This can be done in config now if you want. Just change the Increment on the master branch to Minor