Honor read and write params to begin_transaction

[gmacon]

In my application, I saw an error where a transaction containing only AQL would fail because the write collections were not declared. I traced this to the read and write parameters to begin_transaction not being passed all the way through to the database in commit.

[coveralls]

Coverage decreased (-0.1%) to 99.893% when pulling 0bffcff on gmacon:transaction-aql into 51b0060 on joowani:master.

[coveralls]

Coverage remained the same at 100.0% when pulling 63813bd on gmacon:transaction-aql into 51b0060 on joowani:master.

[joowani]

Thank you for the PR @gmacon!