MountService: Massive bloat reduction and rewrite

- Most API calls now return an int as a result code (see MountServiceResultCode.java)
- All notification code has been removed
- All settings code has been removed
- Removed UMS centric API calls in favor of more generic 'shares'
- Mount error reporting is no longer done via an event, but is done as part of the
  actual mount process
- Rework vold IPC commands to be more sane

Updated:
    MountService: Rename MountServiceObserver -> MountServiceListener
    MountService: Add support for Async callbacks

Updated:
    MountService: Add BinderDeath handling

Updated:
    MountService: Remove notifys since we dont listen anyways

Updated:
    MountService: Fix bad cast

Signed-off-by: San Mehat <san@google.com>