bug 433 NPE in onGlobalContextUpdated of ControllerContext class

Input parameter of type SchemaContext of method onGlobalContextUpdated is
now checked if is different from null to be able to call getOperations method.
In addition clearing of map of rpcs was added.

Change-Id: I2b69d7f50acba041ade17acba8b3f2af7b3e4d9c
Signed-off-by: Jozef Gloncak <jgloncak@cisco.com>
Merge "bug 433 NPE in onGlobalContextUpdated of ControllerContext class"