IMGAPI-532: Empty logs in /var/log instead of deleting them. Fixes #9
IMGAPI-532: Empty logs in /var/log instead of deleting them. Fixes #9

This also eliminates the need to recreate the /var/log/wtmp file when
cleaning up.

joyent/sdc-imgapi,joyent/sdc-imgapi,joyent/sdc-imgapi