Add more operations to account transfer history

[abitmore]

Includes:

• convert_operation
• fill_savings_withdraw_operation (new vop is needed)
• to field for cancel_transfer_from_savings_operation

[mvandeberg]

I agree these do need to be added, but because it is a non-consensus change that effects our UI API call only, I am going to go ahead with the release and get these into develop at a later date.

[abitmore]

While the first 2 can be added later, however, the 3rd one, cancel_transfer_from_savings_operation now has no to field, so a bit hard to notice the receiver if a transfer is cancelled.

Perhaps better to put it in a new issue.

Furthermore, as @arhag suggested, perhaps it's better to process "impacted" in operation evaluators.

[abitmore]

Need a vop for expire_escrow_ratification

[jcalfee]

The transfer to, from, and cancel savings operations are appearing in the account history now..