Workflow enhancements

Major reorganization of core features to improve workflow patterns.

• Removes observableDefaults and addObservable APIs.
• Renames former "observable" model methods to hasComputed, removeComputed, and clearComputeds.
• Adds viewModel property to view as sanctioned store for view-specific data.
• Adds computeds hash table to view for defining computed view properties.
• Adds static mixin APIs for applying Epoxy configuration to other base classes.
• Adds dependency injection to computed getters defining a deps array.
• Adds two-way data exchange to binding filters, and adds integer, decimal, and csv filters.
• Configures class constructors to pull configuration out of passed options.
• Revised documentation.