Fix bdd some sentences

Depends and is needed by:
> ezsystems/ezpublish-kernel#820 [merged]
ezsystems/demobundle#31
Since this PR changes the page mapping to lower cases, it will affect all tests (in this case, setup wizard, and demo content)

Mostly some RegEx and methods names fixes

And adding sentences for:
- click at image
- verify if is homepage ("/")

Make page identifiers not to be case sensitive
- [x] change on FeatureContext
- [x] change on BrowserContext
- [x] change on Demo FeatureContext (PR: ezsystems/demobundle#31) ~~(actually this needs to be done after)~~ (they are both needed)
- [x] change on Legacy FeatureContext (PR: ezsystems/ezpublish-kernel#820)