Added new EventExtensions to BaseModel and BaseCollection

This adds onAndTrigger and listenToAndTrigger methods to BaseModel and
BaseCollection to listen to and trigger an event in one method.
Added initial Relations extensions

This allows declarative setup of relations between models. Currently
only HasMany types are supported.

The config is similar to Backbone.RelationalModel but we're avoiding use
of that library for now as it tends to be a bit heavy.
Added Todo relationship to Project model

This uses the new Relation extensions from trabian-webapp-core.
Moved app/views/projects/project to list_item

There was some ambiguity about the intent of ./project vs. ./detail. By
changing ./project to ./list_item it's more clear what the purpose is.
Template for project list
Fixed typo on ProjectsController test
Project detail controller action and view