Actually use new temp directory.

Previously some of the environments tests were creating temporary directories
for environments but still using the default $confdir to find the environments
directory. This patch replaces the use of $confdir with #{tempdir} as I suspect
was intended by the test author. Seems like another solution would be to set
$confdir to the value of #{tempdir} but I'm not sure what the best way to do
that is so there ya have it.

Signed-off-by: Wayne <wayne@puppetlabs.com>