Compatibility with mercurial plugin 1.50, filtering hg branches by age

Hi

The mercurial plugin v1.50 stores the branch in a different place, my fix should work for both versions
Also, I needed a way for ignore old branches and added a 'maxbranchage' field to the yaml file which specifies the max allowed age of the last commit to any branch in days. Set to 0 to get all branches.