Use stricter is_displayed waits on the <sections> in gallery app object

The test_gallery_return_to_tile_view fails intermittently.

This pull addresses this but also adds in waits in other points for the <section> elements to become displayed , generally should make this suite a bit more robust.


`v1-train` -> Tested, OK to merge.
`v1.0.1` -> Tested, OK to merge.
`desktop` -> Untested