* Refactoring

* Fix issue that causes a new image store to be created at every start of ucloud-api.
* VM Migration API call now takes hostname instead of host key.
* StorageHandler Classes are introduced. They transparently handles things related to importing of image, make vm out of image, resize vm image, delete vm image etc.
* Loggers added to __init__.py of every ucloud component's subpackage.
* Non-Trivial Timeout Events are no longer logged.
* Fix issue that prevents removal of stopped VMs (i.e VMs that are successfully migrated).
* Improved unit handling added. e.g MB, Mb, mB, mb are all Mega Bytes.
* VM migration is now possible on IPv6 host.
* Destination VM (receiving side of migration of a vm) now correctly expects incoming data on free ephemeral port.
* Traceback is no longer output to screen, instead it goes to log file.
* All sanity checks are put into a single file. These checks are run by ucloud.py before running any of ucloud component.

common/helpers.py

@@ -1,5 +1,9 @@
 import logging
 import socket
+import requests
+import json
+
+from ipaddress import ip_address
 
 from os.path import join as join_path
 
@@ -37,3 +41,14 @@ def get_ipv4_address():
             address = s.getsockname()[0]
 
     return address
+
+
+def get_ipv6_address():
+    try:
+        r = requests.get("https://api6.ipify.org?format=json")
+        content = json.loads(r.content.decode("utf-8"))
+        ip = ip_address(content["ip"]).exploded
+    except Exception as e:
+        logging.exception(e)
+    else:
+        return ip