improvements on api for plugins

this change contains following changes:

1. get_labels implementation for stable plugins;
2. improvements in exposing list of plugins: now
it returns detailed info about labels also;
3. fixed minor validation issue with name parameter
of validator.
4. validations on labels on cluster creation,
cluster scaling and launching jobs.

blueprint: plugin-management-api
Change-Id: I8baf6b60f3be1c5ed81758712258b65c4d30e443

sahara/plugins/vanilla/plugin.py

@@ -13,6 +13,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import copy
+
 from sahara.i18n import _
 from sahara.plugins import provisioning as p
 from sahara.plugins.vanilla import versionfactory as vhf
@@ -34,6 +36,14 @@ class VanillaProvider(p.ProvisioningPluginBase):
     def get_node_processes(self, hadoop_version):
         return self._get_version_handler(hadoop_version).get_node_processes()
 
+    def get_labels(self):
+        default = {'enabled': {'status': True}, 'stable': {'status': True}}
+        result = {'plugin_labels': copy.deepcopy(default)}
+        result['version_labels'] = {
+            version: copy.deepcopy(default) for version in self.get_versions()
+        }
+        return result
+
     def get_versions(self):
         return self.version_factory.get_versions()