Not treating serialized field changes differently than other fields

Working on getting a better change upstream into rails (active_record)

This only saves fields to the database that are marked as changed via: `field_will_change!` or `field=new_value`

NOTE:
Bundler isn't able to find arel 3.0.2 so I'm not able to run the tests.

ALSO:
I'm not sure if I have the pull request off of the correct branch. please double check this.