Fixed issues with Swift reset

Put the Swift restore into a try-finally block so the services get started
even if the restore fails.

Ignore failures when backing up recon files, since they doesn't have to exist
if recon is not configured.
Fixed SELinux relabelling after Swift reset

Swift reset makes a backup of the nodes before the tests start and copies them
back after the tests. However, this makes it lose SELinux labels (see ls -Z)
and so rsync fails because of AVC denials. Thanks to this patch, reset now runs
restorecon on /srv/node after the backup was restored.