Add IDs to notes

[KrishnaSolo]

Notes should have id's to prevent over writing the entire notes body everytime we update one note. Also as a result we should support CRUD at note level.

The focus for now - to add id on put request.
The notes field in DB will be a map and the id
will be used to index the map. The value associated with the ID key will be a note object with an id field holding the key and a header and content field representing the note.