First cut at server-side 3-series graphs.
Merge pull request #5 from rhayes-cida/master

First cut at server-side 3-series graphs.
Merge remote-tracking branch 'usgs_upstream/master'

Conflicts:
	dj_eden_app/hydrograph.py
revert to previous version of hydrographs.py
added a function to display dry level on server side plots. it seems it
was beaten to the punch. =)