fix: ironfan discovery too slow

- made test cases wor
- pruned list of clusters before calling broker.discover!
- tweaked discovered item caching

Squashed commit of the following:

commit 0d9b0b49472d566bb29dab4265d2e9a985c8b8d2
Author: Chris Howe <howech@infochimps.com>
Date:   Wed Mar 26 12:03:01 2014 -0500

    fixed the broken test cases

    Change-Id: Ibdcc1d87ce551c5b6cad13b801a3f7c2023c2843

commit fc37cee29600cda5a5e8af3ef7b4f8a8727bc33c
Author: Chris Howe <howech@infochimps.com>
Date:   Wed Mar 26 11:13:59 2014 -0500

    pruned list of clusters before calling broker.discover!, tweaked discovered item caching.

    Change-Id: Ie2e51ca6055b6f0352520c09906a4de9db538a41

Change-Id: Ic097c3687b1bae2946e51673e7a9c7b69b4291d2
Merge "fix: ironfan discovery too slow" into rc