Fix ability to sign in via github

Author: Gaurav0

app/routes/gist-base-route.js

@@ -32,6 +32,8 @@ export default Ember.Route.extend({
 
     showRevision() {},
     showCurrentVersion() {},
-    signInViaGithub() {}
+    signInViaGithub() {
+      this.send('signInWithGithub');
+    }
   }
 });

app/routes/gist.js

@@ -99,7 +99,7 @@ export default Ember.Route.extend({
       });
     },
 
-    signInViaGithub() {
+    signInWithGithub() {
       this.session.open(this.get('toriiProvider')).catch(function(error) {
         if (alert) {
           alert('Could not sign you in: ' + error.message);