Remove ucloud_common and put its files under ucloud.common subpackage.

Remove individual config.py used by every component and put them into single config.py ucloud/config.py
Use /etc/ucloud/ucloud.conf for Environment Variables
Refactoring and a lot of it
Make ucloud repo a package and different components of ucloud a subpackage for avoiding code duplication.
Improved logging.

common/counters.py

@@ -0,0 +1,21 @@
+from etcd3_wrapper import Etcd3Wrapper
+
+
+def increment_etcd_counter(etcd_client: Etcd3Wrapper, key):
+    kv = etcd_client.get(key)
+
+    if kv:
+        counter = int(kv.value)
+        counter = counter + 1
+    else:
+        counter = 1
+
+    etcd_client.put(key, str(counter))
+    return counter
+
+
+def get_etcd_counter(etcd_client: Etcd3Wrapper, key):
+    kv = etcd_client.get(key)
+    if kv:
+        return int(kv.value)
+    return None