bump mdm version to 0.15.2

This changes does not really affect framework
it is a change for pro functionality
just keeping us inline
Merge pull request #1901 from dmaloney-r7/feature/task_assoc/reports

Passing locally, was only failing on the lack of 0.15.2 MDM, which is now pushed to RubyGems. Failing now on an unrelated rake install issue, not sure what's up with Travis.