Modify active "geophysical parameters" tab

If a user has chosen a time step, then make that tag active when
exporting multiple sites.
Moving .txt to .rtf files

To facilitate viewing files on Windows.
Get list of parameters

We’d lost the list along the way…update code.
Update data descriptions.
Adding new Source tab

* No data available to download, but contains info on how to get Imiq
source data.
* Changing Geophysical Parameters to Summary Data Products.
Changing drop down name.

Geophysical Parameters -> Measurements
Updating panel title.
Minor text update.
Adding period at end of sentence.
Merge branch 'master' into update-filecontent

Conflicts:
	app/views/maps/index.html.haml
trying to simplify the export form views
Merge pull request #20 from gina-alaska/update-filecontent

Update filecontent