feat: add extension data at request creation

[benjlevesque]

This enables creating a request with payee/payer delegates, instead of adding them after creation

[coveralls]

Coverage remained the same at 88.26% when pulling 650031173d11d8b44f0b644bab1686b37be70ba3 on create-with-delegate into f0ee19f1fc9b2fd2ae36bc2c8d4305fade06771b on master.