[python3] make sure staticcontroller returns a bytes instance
The ``publish()`` method of controller is supposed to return a
bytes intsance. Returning a text_type instance will crash later
on in the Pyramid response handler when assigning content to
``response.body`` (at least in Python3)::
>>> from pyramid.response import Response
>>> r = Response()
>>> r.body = ''
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/home/adim/.virtualenvs/…/response.py", line 562, in _body__set
raise TypeError(msg)
TypeError: You cannot set Response.body to a text object (use Response.text)
^build$
^dist$
\.egg-info$
^.tox$
^.cache$
\.pyc$
\.pyo$
\.bak$
\.old$
\~$
\#.*?\#$
\.swp$
^doc/book/en/apidoc$
\.old$
\.pybuild
cubicweb/server/test/data/slapd.conf
debian/python-cubicweb
debian/*.log
debian/*.substvars
debian/cubicweb-doc
debian/cubicweb
debian/files
syntax: regexp
.*/data.*/database/.*
.*/data/ldapdb/.*
.*/data/uicache/
.*/data/libpython/cubicweb_.*/i18n/.*\.po
^doc/html/
^doc/doctrees/
^doc/book/en/devweb/js_api/
^doc/_build
^doc/js_api/
test-results.xml