Fix tests, add remove_public_key

The tests for VitualMachineSerializer were wrong. The manager now
contains a function to remove public keys from a user

opennebula_api/models.py

@@ -479,3 +479,45 @@ class OpenNebulaManager():
 
         except ConnectionError:
             raise
+
+    def remove_public_key(self, user, public_key=''):
+        """ 
+
+        Args: 
+            user (CustomUser): Dynamicweb user 
+            public_key (string): Public key to be removed to the user
+
+        Raises:
+            KeyDoesNotExistsError: If replace is False and the user already has a
+                public key 
+            WrongNameError: If no openebula user with this credentials exists
+            ConnectionError: If the connection to the opennebula server can't be
+                established 
+
+        Returns:
+            True if public_key was removed
+
+        """
+
+        try:
+            open_user = self._get_user(user)
+            try:
+                old_key = open_user.template.ssh_public_key 
+                if public_key not in old_key:
+                    raise KeyDoesNotExistsError()
+                if '\n{}'.format(public_key) in old_key:
+                    public_key = old_key.replace('\n{}'.format(public_key), '')
+                else: 
+                    public_key = old_key.replace(public_key, '')
+
+            except AttributeError:
+                raise KeyDoesNotExistsError()
+                
+            self.oneadmin_client.call('user.update', open_user.id,
+                         '<CONTEXT><SSH_PUBLIC_KEY>{key}</SSH_PUBLIC_KEY></CONTEXT>'.format(key=public_key))
+            return True
+        except WrongNameError:
+            raise
+
+        except ConnectionError:
+            raise