bug fix.

微博时间线列表每个条目均可点击了，并且每个条目里每个可点击的都有自己的监听事件。
refactors.
fix the actionbar menuitem' s selector issue.

see my post answer on stackoverflow for detail:
http://stackoverflow.com/questions/13652368/using-a-selector-for-a-menuitem-in-the-actionbar/21911466#21911466

also, refactor the selector' s name:-)
make the drawer' s latest tweet clickable!

also, a little refactors for var defined.