Bug fix

bug fix: more than 2 like on post

Notification service

Added notification service that communicates with user-services aync via apache kafka

Likes api

Basic like on the backend side. Created for future recommendation engine.

Testing

basic testing for foundation and business layer. Some of them require for eth testnet to run

Media support for the backend

May contain some bugs, especially in caching and in frontend app (but I don't care about front).