runlevel check in upstart is broken
runlevel check in upstart is broken

This reverts commit d73a82c2519095b1ae9aa04eaeb205308897cf3c from #309. As pointed out in the issue and comments, many upstart services don't even supply a runlevel or control startup based on some other parameter than runlevel, e.g.:

`start on virtual-filesystems` (/etc/init/udev.conf)

`start on started networking` (/etc/init/rabbitmq-server.conf)

Perhaps a separate `.with_runlevel` could be added instead, but the default check for a service enabled on ubuntu should not look for a runlevel.

elibus/specinfra,mactkg/specinfra,tacahilo/specinfra,mizzy/specinfra,serverspec/specinfra,RoboticCheese/specinfra,sorah/specinfra,chorrell/specinfra,verisign/specinfra,r7kamura/specinfra,miketheman/specinfra,hideyuki/specinfra,glenux/contrib-specinfra,stoned/specinfra,aibou/specinfra,ihassin/specinfra,pfaffle/specinfra,electrical/specinfra,minimum2scp/specinfra,uroesch/specinfra,seroron/specinfra,gh2k/specinfra,hfm/specinfra,higanworks/specinfra,chef-partners/specinfra-cisco,thenexus6/specinfra,chinthakagodawita/specinfra,k0kubun/specinfra,winebarrel/specinfra,sean-horn/specinfra,sergueik/specinfra,stefanhorning/specinfra,edolnx/specinfra,bodgit/specinfra,lurdan/specinfra,nurse/specinfra