Implement user settings
Merge branch 'feature/usercache' into feature/user-settings
Add user setting stuff to component code
Fix logging bug
Fix set_user_setting so it also creates a new setting where necessary and doesn't just update an existing one, and also send notifications on DND status when the user settings indicate that this is desired
Fix component code so that the last modified date for user settings is set correctly
Add documentation for user settings-related API calls
Add documentation for possible user settings
Merge branch 'feature/user-settings' into develop

Conflicts:
	src/envoyxmpp/component.py