Add checks for mandatory arguments in LS2 APIs

Send luna error message if a mandatory argument in a LS2 API is missing

Open-webOS-DCO-1.0-Signed-off-by: Sapna Todwal <sapna.todwal@palm.com>

Change-Id: Ia91c7f9c91a4f777abb037ef128407a26e9b3916
Reviewed-on: http://g2g.palm.com/1536
Reviewed-by: Build Verification
Tested-by: Sapna Todwal <sapna.todwal@palm.com>
Reviewed-by: Keith Derrick <keith.derrick@palm.com>