fix(demo): Update slider demo to work in IE11

Closes #653.

Author: franzsilva

src/components/slider/demoBasicUsage/index.html

@@ -3,7 +3,7 @@
   <md-content class="md-padding">
 
     <h3>
-      RGB <span style="border: 1px solid #333; background: rgb({{color.red}},{{color.green}},{{color.blue}})">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span>
+      RGB <span ng-attr-style="border: 1px solid #333; background: rgb({{color.red}},{{color.green}},{{color.blue}})">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span>
     </h3>
 
     <div layout>