installation: secret key creation fix
installation: secret key creation fix

* Fixes problems with running `inveniomanage config *` without
  CFG_SITE_SECRET_KEY being manually set before. One is able to
  overwrite application config variable SECRET_KEY by passing equally
  named argument to application factory even if the global variable is
  not set.

Signed-off-by: Jiri Kuncar <2bdffcb416fed3002465740d19a053a39918cbe5@cern.ch>
Tested-by: Tibor Simko <c7116e45300b163846dc01f3ed02116e3f8ef7a5@cern.ch>

inveniosoftware/invenio-base,tiborsimko/invenio-base,inveniosoftware/invenio-base,tiborsimko/invenio-base