Fix "Cannot find a resource matching link[/etc/quantum/plugins/...]" (bnc#830870)

In some cases (if :quantum_server is false) we subscribed to
resources before they were defined.

Moved the subscription to a late point when the link and the main
config file are defined.

https://bugzilla.novell.com/show_bug.cgi?id=830870
Merge pull request #97 from mvidner/link-plugin-cfg-path

https://github.com/crowbar/barclamp-quantum/pull/97

Merged by devtool for cloudsleuth