Add CSS fallback properties and remove introjs-ie.css file

Author: afshinm

introjs-ie.css

@@ -3,6 +3,8 @@
   z-index: 999999;
   background-color: #000;
   opacity: 0;
+  -ms-filter: "progid:DXImageTransform.Microsoft.Alpha(Opacity=50)";
+  filter: alpha(opacity=50);
   -webkit-transition: all 0.3s ease-out;
      -moz-transition: all 0.3s ease-out;
       -ms-transition: all 0.3s ease-out;
@@ -21,7 +23,9 @@
 .introjs-helperLayer {
   position: absolute;
   z-index: 9999998;
+  background-color: #FFF;
   background-color: rgba(255,255,255,.9);
+  border: 1px solid #777;
   border: 1px solid rgba(0,0,0,.5);
   border-radius: 4px;
   box-shadow: 0 2px 15px rgba(0,0,0,.4);