Remove double quote for keyframe name(Bugfix)

Remove double quote for keyframe name(Bugfix) - Which resolve the issue of @Keyframes missing name error(which also occur in meteor)

Author: juliosueiras

introjs.css

@@ -440,7 +440,7 @@ tr.introjs-showElement > th {
  }
 }
 
-@-webkit-keyframes "introjspulse" {
+@-webkit-keyframes introjspulse {
  0% {
     -webkit-transform: scale(0);
     opacity: 0.0;