Fix request multipart logging when only 1 part is present

Fix request multipart logging when only 1 part is present

Test to see if the request parameter value is a cherrypy Part
class. This was already being done for the case where the value was a
list, but it was omitted for single values. Logic was combined into new
local function print_param().

Changed the test for the class back to using

    if isinstance(item, cherrypy._cpreqbody.Part):

instead of:

    if getattr(item, "part_class", None):

because using isinstance() clearly indicates what is being done. The
use of getattr() was introduced to prevent a pylint warning concering
use of protected values. The getattr() hack is confusing and proably
not robust if the class implementation changes. The patch now disables
this warning. I cannot explain why cherrypy marks these modules as
protected when clearly one has to utilize them and they are documented
in the cherrypy API doc. Disabling the warning seems the cleanest and
most robust approach.

Signed-off-by: John Dennis <jdennis@redhat.com>
Reviewed-by: Simo Sorce <simo@redhat.com>