typo
extract mixin for `revoked` status tests
add 'aborted' and 'withdrawn' statuses
add migration script to add valid enum values
add status descriptions to the spec
fix repeated status

I had re-organized these statuses a bit and not saved the file..
consolidate cancellation statuses
spec: wording changes to status descriptions
give more specific cancellation error message
Merge pull request #50 from mark-burnett/revoke-synonyms

Add synonyms for 'revoked' status