reverting form-serialize upgrade to address another regression
properly passing the transformer function if supplied
adding test to account for transformer param
version bump + changelog update
Merge branch 'release/0.1.2'
Merge tag '0.1.2' into dev

v0.1.2 hotfix release
 * reverts [form-serialize](https://github.com/dominicbarnes/form-serialize) temporarilly (to address regression)
 * properly handles the `transformer` param for `Form#serialize()`