global: conf variable from ENV, parsing fix
global: conf variable from ENV, parsing fix

* FIX Fixes the way configuration variables are parsed from ENV. It now
  uses the same method we are using in `inveniomanage config set`. This
  fixes the problem that `False` is not parsed correctly.

Signed-off-by: Marco Neumann <3829486b93ec44395f0b980424bae9b6fb07b7bc@crepererum.net>

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