Make site usable for IE8 folks

Changed indexOf to jQuery alternative that internally
  uses native indexOf if that is available

Modify CSS to display default background-color - makes button
  non-transparent in IE

Signed-off-by: Aleksandrs Ļedovskis <aleksandrs@ledovskis.lv>
Merge pull request #131 from aledovsky/bug/ie8_fixes

Make site usable for IE8 folks