Improvements/fixes to MockSocket.
Improvements/fixes to MockSocket.

dmitriy-serdyuk/fuel,dribnet/fuel,dmitriy-serdyuk/fuel,dribnet/fuel,markusnagel/fuel,capybaralet/fuel,vdumoulin/fuel,udibr/fuel,mila-udem/fuel,markusnagel/fuel,janchorowski/fuel,vdumoulin/fuel,mila-udem/fuel,aalmah/fuel,janchorowski/fuel,udibr/fuel,aalmah/fuel,capybaralet/fuel