Replace column_for_attribute with column#type_cast.
Getting the test suite to work with both 3.2.x and 4.x. Use minitest when > 4.0 and use test/unit otherwise.

To run with 3.2.x:
    AR_VERSION=3.2 bundle update activerecord && AR_VERSION=3.2 bundle exec rake test:mysql2

To run with 4.1.x:
    
    AR_VERSION=4.1 bundle update activerecord && AR_VERSION=4.1 bundle exec rake test:mysql2