Selenium / QUnit miscellaneous tests

[StephenChan]

• [ ] CPC export: The CPC prefs form should be hidden or not based on prev-CPC status (moved from issue #157). (Note: there is already an assert_cpc_prefs_in_browse test that checks for this, but it checks for style attrs equal to display: none;, which is kind of unwieldy.)
• Annotation area edit (moved from issue #155):
  • [ ] Drag the resize handles and ensure the text fields update accordingly.
  • [ ] Ensure the drag extremities are where they should be.
  • [ ] Type in the text fields and ensure the resize handles move accordingly.
  • [ ] Text field errors: non-integers, beyond min/max, min greater than max.
• [x] Asychronous generation of thumbnails: Poll the server multiple times until all thumbnails on the page are generated (moved from issue #155). (Tests added in PR #538)

Also see issue #55, which covers the annotation tool.