Response format of reimage/provision requests

Closes-Bug: #1373275

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: I9b1dd237bf74367fd54630a4234af1ad6c0c6f73
Merge "Response format of reimage/provision requests"