v2.0.0

This version makes the library more strictly adhere to the Bai2 specification but provides configuration options to configure certain.

Changes:

• Add parameters for whether or not we use account summaries for the account control checksum. We now include it by default. To disable it account_control_ignores_summary_amounts should passed into options This is the only breaking change.
• Allow for optional "as of" times on the Group header.