Bug 1046209 - Part 1: Rename TabsTray to TabsListLayout (r=lucasr)

--HG--
rename : mobile/android/base/tabs/TabsTray.java => mobile/android/base/tabs/TabsListLayout.java
Bug 1046209 - Part 2: Extract TabsLayout interface (r=lucasr)
Bug 1056169 - Factor out TabRow and rename it to TabsLayoutItemView (r=lucasr)