DDST-70: Fix use of batch methods from decorated services.

[adam-vessey]

GitHub Issue: Fixes Islandora/documentation#2320

• Other Relevant Links (Google Groups discussion, related pull requests,
  Release pull requests, etc.)

What does this Pull Request do?

Fix use of batch methods from decorated services.

What's new?

Moved the serialization of the batch processor back to the form class, instead of attempting to serialize the service info into the batch definitions proper.

• Does this change add any new dependencies? No.
• Does this change require any other modifications to be made to the repository
  (i.e. Regeneration activity, etc.)? No.
• Could this change impact execution of existing code? Highly unlikely.

How should this be tested?

Regression test using the batch child and media upload forms.

Documentation Status

• Does this change existing behaviour that's currently documented? No.
• Does this change require new pages or sections of documentation? No.
• Who does this need to be documented for? Nobody? Devs? Shrug?
• Associated documentation pull request(s): ___ or documentation issue ___

Additional Notes:

Any additional information that you think would be helpful when reviewing this
PR.

Interested parties

Tag (@ mention) interested parties or, if unsure, @Islandora/committers

[alxp]

Tested batch child and batch media upload and both work as expected.