Merge pull request #19 from RouR/master

docs
Added logo on the front page
types of logos
Merge pull request #21 from IliaSauer/master

Logo proposition
Update README.md
Commentary DAO and service

Additional relations and models/DAO/services improvement
Fixed deletion test and added tests for enhanced functionality

Constraint checks and error handling for services

Constraint tests, tests structure improvement
Merge pull request #20 from AlexWyrm/master

Additional relations and models/DAO/services improvement
Fixed deletion test and added tests for enhanced functionality
added angularjs for loading commentaries