initial implementation of attribute managers
add missing test for bad argument passed to BooleanAttr
adding support for integer
adding support for string attrs
extract out module for common attr methods
use shared examples for the :allow_nil option
remove unnecessary default options
adding support for array attrs
adding support for hash attrs
add missing string parsing test for integers
adding support for float attrs
use eql to tests for the correct type and value
pass the attr method_name in the prepare method
add support for model attr
pass a block through to prepare
handling array attrs with blocks
better AttrBlock tests
return AttrMethod value object from AttrBlock
rename AttrBlock to AttrMethods
Use "double" instead of "mock"

I was getting the following warning when running the tests:

    DEPRECATION: mock is deprecated. Use double instead. Called from /Users/t/Documents/GitHub/orgsync/active_interaction/spec/active_interaction/model_attr_spec.rb:17:in `block (4 levels) in <top (required)>'.