[bug 927617] Fix some ui issues with occurrence report

This fixes some ui issues with the report:

1. adds placeholder text for date fields with the date format
2. adds an obvious permalink since the form data is all in querystring
   to make it easier to share report urls between people
3. hides the results unless there are results
4. fixes a problem where if the date fields are malformed, then it
   throws an error
[bug 927617] Add basic tests for occurrences report
Make permalink not blue
Tweak dashboards to remove "color"
[bug 910800] Nix URLField verify_exists arg

This argument was removed from Django.
[bug 910800] Fix test_views to work with Django 1.5

The email_ok is a checkbox field which sends '' or 'on' for data.
This fixes the tests to use that since the validation logic in
Django has changed.