When installing ceph-release log all install failures.

This code used to make an exception for 'already installed' failures
during a ceph-relase install and not log them. Unfortunately, this also
caused all other types of errors to not log at all. With this change
remote.run will log any errors that happen during the command.

Signed-off-by: Andrew Schoen <aschoen@redhat.com>
Merge pull request #397 from ceph/log-install-failures

When ceph-release fails to install for any reason, log it.