Fix for reference frequency bug

I ran this on a quick GW150914 example which had the issue Charlie pointed out (I confirmed this first). Then ran with this branch. It completed and output this:

For the the upcoming Collaboration paper, we would like to re-run soon, using the lalsimulation release that contains the recent PhenomPv3(HM) bugfix. If this parallel bilby fix could be merged, approved and reviewed soon, we would like to pick that up before restarting the runs. Please keep me in the loop.

Thank you!
Frank

mentioned in commit c28659b3

merged