corerel: optimize overlayInsert perf

Instead of doing array.sort() for every insertion, do a binary search and insert. This works since the overlay is always sorted.

For an example model import, runtime was reduced from 2m11s to 37s.
adding scheduling to setBranchHash -> solves burst update issue...
Merge pull request #101 from webgme/overlayInsert_perf

corerel: optimize overlayInsert perf
Bump mongodb version. Fixes #102
Merge branch 'master' into feature/projectMeta