Enabling Flake8 and import sorting

Enabling flake8 verifications in tox.ini and adding import sorting.
All the plugins have been fixed for flake8 errors and the imports
have been sorted.

Change-Id: Icdefe9a877e891a683cc833315e4c3f94fffbab9
Signed-off-by: sousaedu <eduardo.sousa@canonical.com>
diff --git a/RO-plugin/osm_ro_plugin/vim_dummy.py b/RO-plugin/osm_ro_plugin/vim_dummy.py
index fe3a811..f003ba9 100644
--- a/RO-plugin/osm_ro_plugin/vim_dummy.py
+++ b/RO-plugin/osm_ro_plugin/vim_dummy.py
@@ -20,12 +20,14 @@
 Implements a Dummy vim plugin.
 """
 
-import yaml
-from osm_ro_plugin import vimconn
-from uuid import uuid4
 from copy import deepcopy
 import logging
 from random import randrange
+from uuid import uuid4
+
+from osm_ro_plugin import vimconn
+import yaml
+
 
 __author__ = "Alfonso Tierno"
 __date__ = "2020-04-20"