Remove six usage

This repo does not support Python 2 anymore, so we don't need
six for compatibility between Python2 and 3, convert six usage to Python
3 code.

Change-Id: I66624801278c2fbedfe29ed6166f525b3cef1d34

octavia_dashboard/api/rest/lbaasv2.py

@@ -14,7 +14,7 @@
 """API over the neutron LBaaS v2 service.
 """
 
-from six.moves import _thread as thread
+import _thread as thread
 from time import sleep
 
 from django.conf import settings

requirements.txt

@@ -9,4 +9,3 @@ oslo.log>=3.36.0 # Apache-2.0
 pbr!=2.1.0,>=2.0.0 # Apache-2.0
 python-barbicanclient>=4.5.2 # Apache-2.0
 python-keystoneclient>=3.22.0 # Apache-2.0
-six>=1.10.0 # MIT