Implementation of making embedded callbacks optional.

Something to get the discussion started...
Declare type key on polymorphic belongs_to

When a belongs_to association is marked as :polymorphic => true, a model
key of type String for the "type_key_name" field in addition to the key
of type ObjectId for "foreign_key"
Fix type of type_key_name field to be String
Allow passing update options for set and unset modifiers as documented in #416
Merge pull request #414 from md5/declare-belongs_to-type-key

Declare type key on polymorphic belongs_to
Stop clobbering ActiveModel's accessible_attributes method

This works around an incompatibility with Rails 3.2.4+ in which accessible attributes are role-specific (see the ParamsWrapper metal) and need to accept a role argument.

This fix doesn't go all the way down the road of respecting role-specific accessible attributes but silently ignores the passed-in role.
Bug fix: Fixed issue where instance level modifiers don't work on a model with a compound (hash) id key
Added tests for ConfigGenerator. Method app_name reworked to not break tests
Added tests for ModelGenerator
Fixed undefined method 'module_namespacing' for rails 3.0.x
Added --parent option into ModelGenerator
Added TestGeneratorsHelper and test of parent option for ModelGenerator
Kill .project file.
Minor: formatting
Slim down gemfile
Added rails 3.0-3.2 gemfiles for travis.
Change main gemfile to use rails 3.2
Bomb hard when no initializer found.
Added a few details to SCI.

Allows getting the sci parent and root. Needed for scoped identity map
that is shared for sci models.
Rewrite identity map.

More rails and toystore style.