default to 'show all dates'

![screen shot 2014-12-09 at 4 15 57 pm](https://cloud.githubusercontent.com/assets/1757035/5366040/b3f4d8c8-7fbe-11e4-8532-6275f63227b9.png)

Downside is that the select date widget is from bootstrap, so it's complicated to go back to "show all dates" without refreshing once a daterange has been chosen.  Alternative would be to choose whether or not to apply the filter, much like "Date Created" in https://www.commcarehq.org/hq/accounting/accounts/

![screen shot 2014-12-09 at 4 17 59 pm](https://cloud.githubusercontent.com/assets/1757035/5366078/f867e86a-7fbe-11e4-9fa9-a4a53738ffa8.png)

I'm suggesting going with the simple approach for now.