Merge pull request #404 from rashidkpc/master

Fixing grunt build and 0 height bars
Merge pull request #405 from rashidkpc/master

Adding grunt step to CONTRIBUTING.md
Rebased to master to include latest changes

updated the getFlotPairs() function to only check before and after a value, adding only enough zeros to maintain line graphs.
Merge remote-tracking branch 'spencer/zero-filled-ts' into spencer-zero
Fixed subsecond intervals in interval_to_seconds