Fix CacheObserver to expire events.
Fix CacheObserver to expire events.

The Rails API for Observers has changed back and forth over the way the
"observe" call works, between having a separate call for each model and
having a single call for all models, and it's apparently the later.

iamBalaji/Calagator,nblackburn87/calagator,CorainChicago/ActivateHub,bencornelis/calagator,Eugator-Wranglers/calagator,oktober/calagator,shawnacscott/calagator,oktober/calagator,CorainChicago/ActivateHub,jmcduffie32/calagator,alexbeeken/calagator.org,bencornelis/calagator,shawnacscott/calagator,oktober/calagator,Villag/dentonator,eeeeeean/windchimes,reidab/calagator,nblackburn87/calagator,L2-D2/calagator,eeeeeean/windchimes,kerrizor/calagator,iamBalaji/Calagator,nblackburn87/calagator,cp/calagator-1,matthewkmayer/calagator,cp/calagator-1,alexbeeken/calagator.org,L2-D2/calagator,VolunteerOdyssey/calagator,shawnacscott/calagator,jmcduffie32/calagator,iamBalaji/Calagator,L2-D2/calagator,shawnacscott/calagator,matthewkmayer/calagator,cp/calagator-1,kerrizor/calagator,dudleysr/calagator-workspace,iamBalaji/Calagator,CorainChicago/ActivateHub,oktober/calagator,VolunteerOdyssey/calagator,matthewkmayer/calagator,dudleysr/calagator-workspace,reidab/calagator,L2-D2/calagator,VolunteerOdyssey/calagator,kerrizor/calagator,matthewkmayer/calagator,reidab/calagator,CorainChicago/ActivateHub,jmcduffie32/calagator,reidab/calagator,jmcduffie32/calagator,kerrizor/calagator,bencornelis/calagator,Villag/dentonator,bencornelis/calagator,Villag/dentonator,cp/calagator-1,Eugator-Wranglers/calagator