[bug 948998] Fix bigram links with no start dates

[willkg]

This hard codes the start date for bigram links to the dashboard to
2013-01-01 which is a hack to force the dashboard to show all of the
responses with this bigram.

I was going to work through a more serious solution but, as I explain in the comment, there doesn't seem to be a compelling reason to do a more serious solution right now. Ergo, go for the hack now and change it later if need be.

Quick r?

[willkg]

Easy way to test:

1. log in
2. click on "analytics dashboard" tab
3. click on the occurrences report link
4. type in a valid product and a valid search for your data--but don't specify date start or date end
5. click on a bigram link

In the upper left hand section of the dashboard, the start date should be 2013-01-01 and the dashboard graph should look crazy because it's trying to show a year's worth of data in one tiny graph.

[rlr]

the fix WFM. r+

[willkg]

Landed in master in c44b5e5 [bug 948998] Fix bigram links with no start dates