Update Nyx minimum dependency to 4.0.0 RC1

- Improve code readability
- Update Nyx minimum dependency check in CMakeLists.txt and README.md

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

Change-Id: Ic55e280bf4fa1ade28b6c31dd3b425ad3ad6bf51
Reviewed-on: http://g2g.palm.com/1266
Reviewed-by: Build Verification
Tested-by: Pekka Ropo <pekka.ropo@palm.com>
Reviewed-by: Timo Aarnipuro <timo.aarnipuro@palm.com>
Reviewed-by: Keith Derrick <keith.derrick@palm.com>