added new mixin to UserLogin extension, fixed bugId:19672 -- removed tooltip image and put html instead of this
used new mixin in ConfirmEmail.scss and did some tweaks in the mixin itself
added new re-usable component: WikiaTooltipIcon
used new WikiaTooltipIcon component in FacebookSignup modal
added option to provide additional class/classes to WikiaTooltipIcon component
used WikiaStyleGuideTooltipIcon component on confirmation page of Special:UserSignup
small refactoring: changed the optional parameter's name from class to classes; added doc comments
resigned from class constant in favour of translatable message
Merge pull request #352 from Wikia/consumer-QB-2-bugid-19672

Looks good for me