Able to add search result to playlist in SearchActivity.
SearchActivity changed to inherits from FragmentActivity to use DialogFragment
in support library v4.
Code copied and modified from onCreateContextMenu and onContextItemSelected
else where in the Apollo.
Current issues:
1.  When hitting new playlist or select existing playlist,
    the search result disappears.
2.  When there's no search result, shuffle all and playlist menu item still there,
    which is kind of strange though no error caused.
Possible improvements:
1.  Calculate list of song when search completed and save it as attribute,
    which can be used to determine whether to show some menu items.