Fix an issue with back button for Followed Tags and List activities

app/src/main/java/app/fedilab/android/mastodon/activities/FollowedTagActivity.java

@@ -95,6 +95,8 @@ public class FollowedTagActivity extends BaseBarActivity implements FollowedTagA
                     });
                     setTitle(R.string.followed_tags);
                     invalidateOptionsMenu();
+                } else {
+                    finish();
                 }
             }
         });

app/src/main/java/app/fedilab/android/mastodon/activities/MastodonListActivity.java

@@ -143,6 +143,8 @@ public class MastodonListActivity extends BaseBarActivity implements MastodonLis
                     });
                     setTitle(R.string.action_lists);
                     invalidateOptionsMenu();
+                } else {
+                    finish();
                 }
             }
         });

app/src/main/java/app/fedilab/android/mastodon/activities/admin/AdminActionActivity.java

@@ -116,6 +116,8 @@ public class AdminActionActivity extends BaseBarActivity {
                         setTitle(R.string.administration);
                         invalidateOptionsMenu();
                     });
+                } else {
+                    finish();
                 }
             }
         });