R1:93e6a9b3caad

Allow subscriptions to cost amounts other than one dollar and twenty three cents

Summary: Ref T6881. Sometimes, goods and services cost arbitrary amounts.

Test Plan: See next diff.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T6881

Differential Revision: https://secure.phabricator.com/D11594