Update mm_project.py

In index_apex_overlays() check that result['records'] is both set and contains values, 
otherwise return success response. Fixes https://github.com/joeferraro/MavensMate-SublimeText/issues/127 
when there are no ApexExecutionOverlayAction results.
Merge pull request #3 from doublesharp/patch-1

Update mm_project.py