[sailfish-browser] Remove pull up gesture to open the overlay

Overlay can be only opened by tapping the address field.

Reasoning being that this overloads the events view opening
gesture.
[sailfish-browser] Don't show chrome when returning to fullscreen web content
[sailfish-browser] Decouple Overlay from web content's fullscreen state
Merge pull request #255 from rojkov/jb24883-2

Decouple Overlay from web content's fullscreen state
Merge pull request #250 from rainemak/removePushGesture

[sailfish-browser] Remove pull up gesture to open the overlay
[sailfish-browser] Add a custom cover when no tabs