Create object for PublishedSpoiledBallot

[keithrfung]

The possible size of spoiled ballots and the information can create a large file for the PlaintextTally. The intent was to use PublishedPlaintextTally but the spoiled information also has to be exported. The plan is to create a PublishedSpoiledBallot that will house these two pieces of information going forward.

• Create PublishedSpoiledBallot and publish_spoiled_ballot that takes CiphertextAcceptedBallot and spoiled information from Plaintext shares
• Revert PlaintextTally back to PublishedPlaintextTally in publish method

[keithrfung]

This issue still stands but there is a lot in flux around serialization and the long term approach.

[keithrfung]

This will change with the serialization approach.