Add the ability to disable events and use relative url in config.

This requires user test before merge!
I don't understand the reasons of this transformations.

If i configure http://myws.example.com and refresh in the page in http://localhost:9001/project/taiga/kanban the url generated to connect web socket events app is ws://localhost:9001/project/taiga/kanban/http://myws.example.com

Which url do you want to generate?