Basic implementation.
Fix conditional in field_blank?
Add some tests.
Add add_filter to query
Simplify statement for easier customization.
Add missing filter methods to query and add queryable helper.
Add application controller patch to include query_class setter.
Fix session key name and operators_for_select helper.
Allow operators_by_filter_type to be set as acts_as_queryable option.
Steal query column from chiliproject.
Make query help use all keys from session.