Response format of reimage/provision requests

Fix:
1)Define a new file to host all error codes.
2)Added error codes to ServerMgrExcpetion.
3)Returned coe,msg and data for all REST API's except GET

Testting:
1)Tested ALL CLI commands.

Change-Id: I5eade971fcf2ff208523a14b74af4902877356e5
Merge "Response format of reimage/provision requests"