Tidy imports per PEP 8.

Change-Id: Ie8f88c6dfabe489572095674dd290603fa9d53e2
Fix title and login selenium tests, part fix registration.

This updates the tests for the current UI version, and adds some
helper methods for getting elements & asserting their display state.
The registration test mostly works, but doesn't seem to show the
div properly for reasons unknown (it works manually).

Change-Id: I6cb4bc292d97777aa021c74be903674f5fb26157