Merge branch '370-nav-drawer-remember-fragment' into 'master'

Remember the selected fragment from the NavDrawer

and stay in it when configuration changes

Closes #370

See merge request !176

briar-android/src/org/briarproject/android/NavDrawerActivity.java

@@ -133,7 +133,7 @@ public class NavDrawerActivity extends BriarFragmentActivity implements
 			}
 		};
 		drawerLayout.setDrawerListener(drawerToggle);
-		startFragment(ContactListFragment.newInstance());
+		if (state == null) startFragment(ContactListFragment.newInstance());
 		checkAuthorHandle(getIntent());
 
 		initializeTransports(getLayoutInflater());