Undo uniquify dygraph csv names

This ended up causing way more issues than I expected, first with missing
graphs, and now it prevents annotations for single graphs from being applied.
Reverting the change altogether.
Rename STREAM .graphs in studies directory

The csv files we generate for dygraphs get their name from the lowecase
basename of the .graph files. We had some duplicate basenames for some stream
tests. This renames the .graph files in the studies directory so we no longer
have a conflict. Previously we would override the .dat files, so the wrong data
was being loaded for some graphs.

An upcoming patch will add a check to make sure we don't run into this again.
Merge pull request #1008 from ronawho/uniquify-dygraph-csv-name

Undo code in gengraphs to make csv files unique

[reviewed by @lydia-duncan]

This was creating a lot more issues than I expected. I'm undoing the change, and changing the names of the .graph files that led to the non-unique csv files. 

The duplicate files were found with an upcoming patch that will make sure we don't run into this again: 323fb989b8ca2711fb15f1c5811d38a9eb8137f5