Get rid of locator in the Responder

[sr-gi]

Check if the locator is necessary in the Responder or not. If not, get rid of it.

[sr-gi]

The only place in the Responder where the locator is needed is when the appointment is completed so the locator_uuid_map cap be properly updated in the db.

Keeping locators in memory imply 16 bytes per appointment, and the current approach required 1 read + 1 write to db to the database in order to update:

• Read locator_uuid_map from db.
• Update locator_uuid_map.

Deleting the locator from memory will reduce the memory requirements for 16-bytes per appointment, at the cost of 1 additional read when data has to be deleted:

• Read appointment from db to get locator.
• Read locator_uuid_map.
• Update locator_uuid_map.