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.

config.py

@@ -0,0 +1,19 @@
+from etcd3_wrapper import Etcd3Wrapper
+
+from common.classes import EnvironmentVariables
+from common.host import HostPool
+from common.request import RequestPool
+from common.vm import VmPool
+
+env_vars = EnvironmentVariables('/etc/ucloud/ucloud.conf')
+
+etcd_wrapper_args = ()
+etcd_wrapper_kwargs = {"host": env_vars.get("ETCD_URL")}
+
+etcd_client = Etcd3Wrapper(*etcd_wrapper_args, **etcd_wrapper_kwargs)
+
+host_pool = HostPool(etcd_client, env_vars.get('HOST_PREFIX'))
+vm_pool = VmPool(etcd_client, env_vars.get('VM_PREFIX'))
+request_pool = RequestPool(etcd_client, env_vars.get('REQUEST_PREFIX'))
+
+running_vms = []