Promising API + Minimal House keeping

[houssem-yahiaoui]

This is PR holds the following :

1 - Minimal house keeping. A - Introducing the Config folder where all Express, Mongoose and future module will be configured into. B - Cleaning the Server.js file under Server folder for SOC sakes.

2 - Since we're configuring mongoose with native promises, i've pushed the call to the max using, Then and Catch for responses and errors + changing the call over the remove with cuid to more native call using findOneAndRemove

Plus the code is well linted and all tests are being passed, i hope this PR will help.