fix(tabs): fix empty href

- Add agreed upon fix for empty href due to CSP and the new Angular router

Fixes #3799

Author: wesleycho

Diff for: template/tabs/tab.html

@@ -1,3 +1,3 @@
 <li ng-class="{active: active, disabled: disabled}">
-  <a href ng-click="select()" tab-heading-transclude>{{heading}}</a>
+  <a href="#" ng-click="$event.preventDefault(); select()" tab-heading-transclude>{{heading}}</a>
 </li>