JSON client: Log pretty-printed request and response with -vv or above
The whole HTTP request is now printed with -vvv or above.
Changes `verbose` in the connection to be the level from api.env,
rather than a boolean value.
For XML-RPC, the whole request will be shown already with -v.
https://fedorahosted.org/freeipa/ticket/4233
Reviewed-By: David Kupka <dkupka@redhat.com>