Add basic apply/revert test coverage

[ChrisSchinnerl]

We need unit test coverage for applying/reverting transactions including the following types of transactions:

For both V1 and V2 transactions:

• Txn with siacoin outputs
• Txn with arbitrary data
• Txn with attestation
• Txn with contract
• Txn with contract revision
• Txn with storage proof
• Txn with siafund outputs

The test(s) should apply the transaction, revert the transaction and then verify the state is the same as before.
These tests should serve as regression tests for some of the panics we have seen before.