Merge branch '2.1' into 2.2

# Conflicts:
#	gns3server/compute/docker/docker_vm.py
#	gns3server/controller/compute.py
#	gns3server/controller/gns3vm/__init__.py
#	gns3server/controller/link.py
#	gns3server/controller/project.py
#	gns3server/handlers/api/controller/project_handler.py
#	gns3server/handlers/api/controller/server_handler.py
#	gns3server/utils/asyncio/__init__.py
#	gns3server/utils/asyncio/telnet_server.py
#	gns3server/version.py
#	gns3server/web/web_server.py
#	tests/compute/qemu/test_qemu_vm.py

gns3server/compute/docker/__init__.py

@@ -25,7 +25,7 @@ import asyncio
 import logging
 import aiohttp
 from gns3server.utils import parse_version
-from gns3server.utils.asyncio import locked_coroutine
+from gns3server.utils.asyncio import locking
 from gns3server.compute.base_manager import BaseManager
 from gns3server.compute.docker.docker_vm import DockerVM
 from gns3server.compute.docker.docker_error import DockerError, DockerHttp304Error, DockerHttp404Error
@@ -187,7 +187,8 @@ class Docker(BaseManager):
                                                          autoping=True)
         return connection
 
-    @locked_coroutine
+    @locking
+    @asyncio.coroutine
     def pull_image(self, image, progress_callback=None):
         """
         Pulls an image from the Docker repository