[devtools] add http_publish to CubicWebTC (closes #2565882)
Fakes a http request, without overriding the normal error handling.
Returns the request object so the caller can check for errors.
option_group_changed('port', 'main', 'web')
option_group_changed('query-log-file', 'main', 'web')
option_group_changed('profile', 'main', 'web')
option_group_changed('max-post-length', 'main', 'web')