Update metasploit-data-models to 0.6.3

This updates activerecord to 3.2.13 due to recent vulns.
Update MDM in gemcache
Merge branch 'bturner-r7/update-mdm' into release

This lands the Mdm update to release. It shouldn't conflict with master
but if it does, please tell todb@metasploit.com how you resolved it.

[See #1620]