Don't get Gist id until needed

Author: kevinsawicki

app/src/main/java/com/github/mobile/ui/gist/GistsViewActivity.java

@@ -116,9 +116,8 @@ protected void onCreate(Bundle savedInstanceState) {
         // Support opening this activity with a single Gist that may be present
         // in the intent but not currently present in the store
         if (gists == null && gist != null) {
-            String id = gist.getId();
             if (gist.getCreatedAt() != null) {
-                Gist stored = store.getGist(id);
+                Gist stored = store.getGist(gist.getId());
                 if (stored == null)
                     store.addGist(gist);
             }