Add support for new avatar storage (#50)

* Add support for new avatar storage,modify the README and android-interact.sh

* Show the nickname for chatroom, fix the IOError in avatar.py

* style change

android-interact.sh

@@ -53,7 +53,7 @@ elif [[ $1 == "db" || $1 == "res" ]]; then
 	if [[ $1 == "res" ]]; then
 		echo "Pulling resources... this might take a long time, because adb sucks..."
 		mkdir -p resource; cd resource
-		for d in image2 voice2 emoji video sfs; do
+		for d in avatar image2 voice2 emoji video sfs; do
 			mkdir -p $d; cd $d
 			adb pull "$RES_DIR/$chooseUser/$d"
 			cd ..