Use flake8 if available instead of pyflakes

With flake8, we can check for more issues and ignore those who are not
real issues.

This allowed me to find genuine errors in:
- modules/boursorama/pages/account_history.py
- modules/ing/pages/login.py
- weboob/tools/application/qt/qt.py
I left one in weboob/tools/browser/browser.py for the time being.

Some PEP8 fixes on other files.

weboob/tools/ordereddict.py

@@ -22,16 +22,15 @@ try:
     from collections import OrderedDict
 except ImportError:
     try:
-        from simplejson import OrderedDict
+        from simplejson import OrderedDict  # NOQA
     except ImportError:
         try:
-            from ordereddict import OrderedDict
+            from ordereddict import OrderedDict  # NOQA
         except ImportError:
             ## {{{ http://code.activestate.com/recipes/576693/ (r6)
             from UserDict import DictMixin
 
-            class OrderedDict(dict, DictMixin):
-
+            class OrderedDict(dict, DictMixin):  # NOQA
                 def __init__(self, *args, **kwds):
                     if len(args) > 1:
                         raise TypeError('expected at most 1 arguments, got %d' % len(args))
@@ -123,7 +122,7 @@ except ImportError:
 
                 def __eq__(self, other):
                     if isinstance(other, OrderedDict):
-                        return len(self)==len(other) and self.items() == other.items()
+                        return len(self) == len(other) and self.items() == other.items()
                     return dict.__eq__(self, other)
 
                 def __ne__(self, other):