TabUI Implementing new AbstractUIComponent methods.

TabUI Implementing new AbstractUIComponent methods.

[Issue#:]   https://bugs.tizen.org/jira/browse/TT-157
[Problem:]  New window management class needs AbstractUIComponent to
            have some view managing functions.
[Cause:]    N/A
[Solution:] Implemented needed methods:
            void init(Evas_Object* parent)
            Evas_Object* getContent()
            void showUI()
            void hideUI()
[Verify:]   Change is not affecting browsers behaviour.

Change-Id: I6d4a91af909722050564690510f64e9c331b7fe5