Square-authentication

- /login_username/v0 is now POST method.
- new flag in /login_username/v0 assign_app_id_if_missing.
- bugfix: /get_user_details/v0 now only returns number of active sessions.

**Full Changelog**: https://github.com/thepmsquare/square_authentication/compare/3.0.0...4.0.0

added new endpoints
/update_username/v0
/delete_user/v0
/update_password/v0
move data in password related endpoints to request body from params.
/register_username/v0 now takes in app_id as optional parameter to assign user to that app and create session for it.
/generate_access_token/v0 now only needs refresh token (removed validation).
/logout/v0 now only needs refresh token (removed validation).
/update_user_app_ids/v0 now only updates ids for self (user). added access token as input param and removed user_id.
/get_user_app_ids/v0 is now /get_user_details/v0 with access token as the only input param.

**Full Changelog**: https://github.com/thepmsquare/square_authentication/compare/2.0.0...3.0.0

- authentication module needs to be used across applications so
- register_username: will not create sessions and therefore will not auto login.
- login: added validation if app is assigned to user before assigning it and added app_id in session row.
- logout: added app_id as new parameter and validation for that.
- generate_access_token: added app_id as new parameter and validation for that.
- added 2 new endpoints
- get user app ids: **access token validation pending**.
- change user app ids: **access token validation pending**.
- add versions for all endpoint paths.
- make it compatible with square_database_helper 2.x.
- username in database will always be lowercase.
- standardise output formats for all api.

**Full Changelog**: https://github.com/thepmsquare/square_authentication/compare/1.0.0...2.0.0