Fix Biggest Memory leaks on Browser application

Working on Issue 31125 (http://code.google.com/p/android/issues/detail?id=31125):
* Enhance bitmap management (add recycle() functions when necessary)
* Enhance mTabViews management on NavScreen class (add remove() function
  when necessary).

Change-Id: I544620484f4ad52e02e4d3f4336a1f007bbdc8fb
Author: Sebastien MICHEL <sebastien.michel@intel.com
Signed-off-by: Xiaokang Qin <xiaokang.qin@intel.com>
Signed-off-by: Bruce Beare <bruce.j.beare@intel.com>
Signed-off-by: Jack Ren <jack.ren@intel.com>
Author-tracking-BZ: 56189