overriden media query to reflect better names and avoid overlappings on variable values
replaced $icon-font-path usages by /fonts/ since it will be
less subject to modification if we migrate to recent versions of
sass-bootstrap someday
Introduced new $screen-tn-max variable to identify devices
having size width lower than 480px (typically iphones, galaxy s etc.. in portrait mode)
Replaced enseirb venue by a img-responsive class
Allowing to pass a $withHover param to @responsive-image mixin
Introduced changes for portrait mobiles in order to display nicely on 320px
devices