add a fake db column for use in type detecting forms
oops, used Ruby 2.0 syntax
throw a more specific error for a bad type
more slug testing, check a working output
Merge branch 'v1.2.0' into fake-columns-for-attributes

Conflicts:
	spec/active_interaction/filter_spec.rb
make filters more self contained by adding column types
make filter column objects flyweight
add documentation for database_column_type
Merge branch 'master' into fake-columns-for-attributes
add a since tag to database_column_type
this returns a symbol, not a string
do not throw an error when the filter is not good

This isn't the place to test for the validity of a filter. This change
also creates a better separation between filter name and database type.
better documentation for database_column_type
add docs for column_for_attribute
add docs for FilterColumn
I believe this is the correct order
add return type documentation to these readers
refactored to be more concise
note the new functionality in the changelog
truncate the object id so I can remove the rubocop pragma