[Android] Add event refresh icon animation

Rotate the refresh icon in the event list fragment when list data is
reloading. More information at
http://stackoverflow.com/questions/9731602/animated-icon-for-actionitem

Signed-off-by: Claudio Matsuoka <cmatsuoka@gmail.com>
[Android] Update TODO list

Signed-off-by: Claudio Matsuoka <cmatsuoka@gmail.com>