Refactoring: switch to API

This pull request contains the following list of features:

User confirmation should use API and registration (used request python module)
Change password page - switched to API
Updating user info page - switched to API
Set privacy page - switched to API
Base API methods. 1) Request 2) login_token -> user_id 3) user_id -> login_token
Impoment password strategy for registration and change pwd // min 6 chars and others
Refactoring(profile_settings) methods // create separately module for all profile settings methods from ser.py
Implemented api method to query users followed/following by username