Adding --force option to the bosco_cluster --add

This allows the user to say what flavor of binaries to install on the
remote system, bypassing the normal auto-detection.
From OSG Jira CAMPUS-78
Replacing SSH Connections with MasterControl SSH

Using the MasterControl SSH eliminates a lot of TCP startups
connections for SSH.

From OSG Jira CAMPUS-82
Fix rsync transfer for Mac clients and fail on rsync error.

From the OSG Jira CAMPUS-71 and CAMPUS-28