Disambiguate items function from items property

The items collection was clobbering the items function.  This makes this
easier to test via Jasmine.
Fix exception after loading a different key

The cause here was the ||= in item_router.coffee.  The itemsCollection
already had the old keypair set so the new keypair wasn't getting set properly.

Added some basic tests for the item_router and fixed the bug.
Merge pull request #97 from ejfinneran/issue-66

Fix exception after changing keypair