[popolemploi] fix : site changed
certhash is not used either at the moment
the ssl check option is not used anymore
cookie is not used anymore
headers is not used anymore..
delete the certificate in the cmb module
delete useless imports
remove dependencie to weboob.tools.parsers
Test "if a is None", not only "if a"
Convert dresdenwetter to browser2
NotAvailable and NotLoaded should not be callable
Rewrite the empty function according to the new NotLoaded

and the new NotAvailableType...
NotAvailable can be now directly set
Introduce CleanChars filter
Display the text if the regexp does not match
Use more tools of browser2 in dresdenwetter
Use more tools of browser2 in dresdenwetter (2/2)
Display GaugeMeasure when level is zero
CleanChars is now an option of CleanText
copy of NotLoaded and NotAvailable returns the same object