accept a la carte create instance group request

accept a la carte create instance group request

Updated postBPELRequest to accept RequestClientParameter
Switched to using .toString rather than .name for enum
Added source to fix failing test
Added action to fix failing apih tests
Removed unused headers from test
Removed unused import from RequestClientParameter
Updated to use instanceGroupId constant
Removed defaulting source in requestInfo
Added validation for mandatory headers
Added test case for modelVersionId in service related instance
Added relatedInstance validation for create instanceGroup
Added unit test cases for MembersValidation
Added test cases for relatedInstances validation
Added tests for add/remove member validation
Added updates for deleteInstanceGroups
Removed serviceProxy from test resource file
Removed ServiceProxy as it is no longer needed
Changed action to be removeMembers in endpoint
Added removeMembers endpoint and validation
Updated validation for create instanceGroups
...

Change-Id: I12b14d6d81dd0690eea33dfcbf1be17c509f9832
Issue-ID: SO-1207
Signed-off-by: Benjamin, Max (mb388a) <mb388a@us.att.com>