implemented view triggers API, made dispatcher property private

Developers can now define a 'triggers' hash in their dispatcher. These bindings are then made availbale to compnents through a .trigger method, which is deinfed in the mixin.
viewTrigger docs
release 0.8.4
fix for watchStores bug

When watchStores property is specified, no change events store were being bound to stores. This fixes that bug.
Fix for eventEmitter memory leak

Only generate promises for stores that ae listening for the action being dispacthed. Otherwise, they will never fire change events, the promise will never be resolved, and the change event listeners will accumulate forever.
Merge pull request #37 from deloreanjs/view-triggers-api

View triggers API