Add unit tests for DeclarativeHistoryModel
[sailfish-browser] Fix history search to return only distinct results
Cleanup DeclarativeHistoryModel to search only from global history

Tab history is not needed anywhere anymore.
Cleanup DeclarativeTabModel::currentTabId related code

Previously this was needed only by HistoryModel but it
does not require this property anymore.
Use common TestObject for DeclarativeTabModel unit tests
Update link data immediately when we are about to navigate

Also title must be always set to the active tab as that block
enables database writting. Go back / forward button are changed
to be blocking, if this turns out to be too intrusive then we
need to figure out something else.

There are still some holes but now database returns quite reliably
good results even if you navigate back and forth quickly.
Merge pull request #82 from rainemak/fixHistory

Fix history search to return distinct results