treewide: specify 'python2' instead of 'python' in shebangs of python scripts

Signed-off-by: Ivan Shapovalov <intelfx@intelfx.name>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>

test/crit-recode.py

-#!/bin/env python
+#!/bin/env python2
 
 import pycriu
 import sys

test/mounts/mounts.sh

@@ -20,7 +20,7 @@ for i in `cat /proc/self/mounts | awk '{ print $2 }'`; do
 	umount -l $i
 done
 
-python mounts.py
+python2 mounts.py
 kill $INMNTNS_PID
 while :; do
 	sleep 10

test/rpc/errno.py

-#!/usr/bin/python
+#!/usr/bin/python2
 # Test criu errno
 
 import socket, os, imp, sys, errno

test/rpc/ps_test.py

-#!/usr/bin/python
+#!/usr/bin/python2
 
 import socket, os, imp, sys, errno
 import rpc_pb2 as rpc

test/rpc/restore-loop.py

-#!/usr/bin/python
+#!/usr/bin/python2
 
 import socket, os, imp, sys
 import rpc_pb2 as rpc

test/rpc/test.py

-#!/usr/bin/python
+#!/usr/bin/python2
 
 import socket, os, imp, sys
 import rpc_pb2 as rpc