Fixes H201: no 'except:' at least use 'except Exception:'

Enabled H201 on tox and changes made in relevant files.

Change-Id: I7e1f05d9f90b11ac89b371e66ed9a0010462ad01

monasca_persister/repositories/persister.py

@@ -73,7 +73,7 @@ class Persister(object):
 
                 if len(self._data_points) >= self._database_batch_size:
                     self._flush()
-        except:
+        except Exception:
             LOG.exception(
                     'Persister encountered fatal exception processing '
                     'messages. '

tox.ini

@@ -26,8 +26,7 @@ commands = {posargs}
 [flake8]
 max-line-length = 120
 # TODO: ignored checks should be enabled in the future 
-# H201  no 'except:' at least use 'except Exception:'
 # H405  multi line docstring summary not separated with an empty line
 # H904  Wrap long lines in parentheses instead of a backslash
-ignore = F821,H201,H405,H904,E126,E125,H306,E302,E122
+ignore = F821,H405,H904,E126,E125,H306,E302,E122
 exclude=.venv,.git,.tox,dist,*openstack/common*,*egg,build