grant role to user: handle admin roles with space

Fix 'Unable to add user' when granted role contains a space:

    $ awx-cli send <<EOF
    [
      {
        "asset_type": "organization",
        "name": "MyOrg",
        "asset_relation": {
          "roles": [
            {
              "name": "Inventory Admin",
              "user": ["misc"],
              "team": []
            }
          ]
        }
      }
    ]
    EOF

    ORGANIZATION [MyOrg] ***
    Asset up to date
    Unable to add user misc to Inventory Admin role: The requested object could not be found.

tower_cli/resources/role.py

@@ -172,7 +172,7 @@ def data_endpoint(cls, in_data, ignore=[]):
         else:
             endpoint = '/roles/'
         if in_data.get('type', False):
-            data['role_field'] = '%s_role' % in_data['type'].lower()
+            data['role_field'] = '%s_role' % in_data['type'].replace(' ', '_').lower()
         # Add back fields unrelated to role lookup, such as all_pages
         for key, value in in_data.items():
             if key not in RESOURCE_FIELDS and key not in ['type', 'user', 'team']: