Update for Mass Storage Mode now being a separate device

- Increment version number to 4.0.0
- Emulator doesn't support Mass Storage Mode, so don't add code to
  create the new device
- Remove all Mass Storage Mode related functionality from System device
- Update nyx-lib version dependency in README.md

Open-webOS-DCO-1.0-Signed-off-by: Pekka Ropo <pekka.ropo@palm.com>

Change-Id: I4e615d6dc8569d095cf7a86a56b334407d8596d3
Reviewed-on: http://g2g.palm.com/1219
Reviewed-by: Build Verification
Reviewed-by: Herb Kuta <herb.kuta@palm.com>
Reviewed-by: Keith Derrick <keith.derrick@palm.com>
Tested-by: Keith Derrick <keith.derrick@palm.com>