Status: Use chat bubbles for user- icons

Replace the colored dot `user-` prefixed icons
with chat bubbles. This more closely follows the
FreeDesktop.org Icon Naming Spec which describes
them as chat icons. Remove non-FD.o `user-` icons.

Fixes issue where the fullcolor and
symbolic icons used different styles.

Closes #1307

Note: Apps that used the dots as general status icons
      should now use the dots found in emblems folder.
      (e.g. use `emblem-disabled` instead of `user-offline`)