node_processes parameter in node group create method should not have default value

[Andrey Pavlov]

node_processes is required parameter and should not have None value by default

Error
_StringException: Traceback (most recent call last):
  File "/home/kshatrix/python-saharaclient/saharaclient/tests/unit/nova/test_shell.py", line 374, in test_shell
    print shl.main(('node-group-template-create --name test1ads2as3 --hadoop-version 2.4.1 --plugin-name vanilla --flavor-id 2').split())
  File "/home/kshatrix/python-saharaclient/saharaclient/shell.py", line 647, in main
    args.func(self.cs, args)
  File "/home/kshatrix/python-saharaclient/saharaclient/api/shell.py", line 448, in do_node_group_template_create
    args.volume_type))
  File "/home/kshatrix/python-saharaclient/saharaclient/api/node_group_templates.py", line 77, in create
    'node_group_template')
  File "/home/kshatrix/python-saharaclient/saharaclient/api/base.py", line 83, in _create
    self._raise_api_exception(resp)
  File "/home/kshatrix/python-saharaclient/saharaclient/api/base.py", line 146, in _raise_api_exception
    error_message=error_data.get("error_message"))
APIException: None is not of type 'array'

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/150773

[OpenStack Infra (hudson-openstack)]

Change abandoned by Andrey Pavlov (<email address hidden>) on branch: master
Review: https://review.openstack.org/150773