[Issue#] https://bugs.tizen.org/jira/browse/TT-132
[Problem] View mode was set as global flag.
[Cause] N/A
[Solution] Added flag for each tab to remeber current mode.
[Verify] Open new tab (google.com), open settings, switch to mobile
mode, page should reload in mobile view.
Change-Id: I19a6f1965938930b45f46b076ce030f2fe9c10ed
Signed-off-by: Maciej Skrzypkowski <m.skrzypkows@samsung.com>