Fixes for timelines and is_displayed()

* Timelines provider_init was not being set up before test_vm was
  attempting to refresh relationships. Made provider_init fixture a
  prerequisite for test_vm instead.
* is_displayed required a title to be set for a Region, but sometimes
  titles are not set as the Region is multipage, as title is not a
  required keyword, at the moment we jsut accept that if title is None,
  then the title matches.
Merge pull request #918 from psav/fix_timelines

Fixes for timelines and is_displayed()