NAWQAAN-162

* Added long term mean line
* Calculating from data, will sub in Casey's data later
* Unable to do hover yet, need to either be clever or hack around a bit
NAWQAAN-162

* Added definition of terms to a JS singleton
* Including terms on full report page
* Pulled out tooltip div factory to private function
* Binding to plothover for line hovers
* May need to tweek threshold based on user feedback
NAWQAAN-162

* Moved term name into object
* Added keys that are better for accessing definitions
* Added def to short and long to specify they are the definitions
Merge pull request #145 from jiwalker-usgs/NAWQAAN-162

NAWQAAN-162