ipapython: remove hard dependency on ipaplatform
Use hard-coded paths to certutil, pk12util and openssl in certdb if
ipaplatform is not available.
Hard-coded the path to setpasswd in ipautil.run() doc string.
Remove ipaplatform dependency from ipapython's setup.py and add ipapython
dependency to ipaplatform's setup.py.
https://fedorahosted.org/freeipa/ticket/6474
Reviewed-By: Stanislav Laznicka <slaznick@redhat.com>