With Python2, properties were all str(). with Python3, we need to distinguish
binary-like properties from text-like properties.

This should ideally be implemented by checking PropertySheet elementary_type
(such as `data` for bytes() and `string` or `text` for str()) for each property.
For now (bootstrap/addERP5Site) though, let's consider all properties in .xml to
be UTF-8 str() and statically define which is which for non-.xml files.

And _mysql/mysqldb API (_mysql.connection.query()) converts the query string to
bytes() (additionally, cursor.execute(QUERY, ARGS) calls query() after
converting everything to bytes() too).

Done through various 2to3 fixers (zope.fixers, modernize, future) and also
contain manual changes. This is a single commit so that we have a clearer
picture of how code converted with my2to3 should look like.

Except straightforward @implementer decorator 2to3 fixer, only product/ folder
was considered as the goal was to be able to create an ERP5Site.

* Use @implementer decorator introduced in zope.interface 3.6.0 (2010):

  The implements syntax used under Python 2.X does not work under 3.X, since it
  depends on how metaclasses are implemented and this has changed. Instead it
  now supports a decorator syntax (also under Python 2.X).

  Applied thanks to 2to3 `zope.fixers` package.

* Use `six.moves` rather than `future` install_aliases() feature because the
  latter use unicode_literals and "wraps" module aliases so that unicode() are
  returned for text rather than str() (Python2 standard library). This notably
  breaks BusinessTemplate code which uses urllib quote() for filesystem paths...

* No more unbound methods in python3 so use six.get_unbound_function().

* dict.(iteritems,iterkeys,itervalues)() => six.\1(dict) thanks to `dict_six`
  2to3 fixer from `modernize`:
  $ python-modernize -w -f dict_six product/

* Manually make sure that dict.{items,values,keys}() returns a real list when
  needed rather than a dict_{items,values,keys} when it is latter modified. By
  default, 2to3 blindly does list(dict.{items,values,keys}()) which is not
  acceptable from performances point of view. With my2to3, this will be possible
  to handle such case automatically.

* past.builtins:
  portal_skins/erp5_core/Base_sortObjectListLikeSQL:0:2:Redefining built-in 'cmp' (redefined-builtin)
* six and six.moves imports:
  + portal_skins/erp5_core/Base_updateListboxSelection:0:2:Redefining built-in 'basestring' (redefined-builtin)
  + portal_skins/erp5_core/ERP5Site_checkDataWithScript:20:2:Redefining built-in 'xrange' (redefined-builtin),

Use the latter form that works on both. On non-PythonScript code, this is of
course not an issue but Python2 PythonScript does not have a __code__ properties
and requires a patch on Shared.DC.Scripts.Signature (applied by SlapOS recipe)
so that FuncCode() object is set to not only func_code but also __code__.

And also disable pylint patch as pylint version with Python3 support is not
supported yet by ERP5...

* Add functions to properly convert/handle bytes/str/unicode (from
  slapos.util) (stricter than six.ensure_{text,str}()).
* Python3 {keys,values,items}() now returns dict_{keys,values,items} rather than
  real list() so add ensure_list() to create a list() when it is latter modified
  but do nothing on Python2 for performance sake.

  File "product/TimerService/timerserver/TimerServer.py", line 71, in run
    s.send('GET / HTTP/1.1\r\n\r\n')
TypeError: a bytes-like object is required, not 'str'

And Zope4 now mandates it to be a string ({Shared.DC.ZRDB.TM.TM,ITransactionManager}.sortKey()).

This changes the API to implement similar feature in Python3, but this should
not be an issue because Interactor are only for non-ERP5 object...

py3: AccessControl users_with_local_roles() returns a dict_keys() instead of a subscriptable object.

Submitted upstream:
  https://github.com/zopefoundation/AccessControl/pull/128

py3: DCWorkflow is python2-only so make ERP5Site creation work on Python3 WITH_LEGACY_WORKFLOW=False.

ERP5 Workflow implementation should ideally not depend on DCWorkflow at all so
that legacy DCWorkflow can be disabled for Python2 but this would require much
more work.

Mainly for maintenance sake and to update the code before porting it to python3.

See merge request !1611

using json in 37b795fb was wrong,
because not all arguments can be converted to json (for example
DateTime instances)

This also enable the format using pprint.pformat for args, instead
of a simple str that was done in ActivityTool_getMessageList.

See merge request !1600

   The portal_skins was choosen to store the images to use proper http
cache.

   It is really not required, so we follow up the same as google oauth.

See merge request !1607

See merge request nexedi/erp5!1608