Cleaning some stuff up from Backbone tutorial.
Fix Bomb validations.
Improved authentication.
No need for the user to see the sign-in or sign-up page if they're logged in already.
authenticate method has been renamed and a conditional added so that it can be repurposed as a simple session check.
Automatically clear existing alerts when creating new ones.
Fixed bomb creation with validation.
Use save callbacks instead of checking object return. This should be more reliable and predictable.