v2.0.0

Breaking:

• Require Node.js 8 05b0479
• Throw error if onCancel is called after promise settlement (#18) c4ebb36
• Refactor TypeScript definition to CommonJS compatible export (#19) 72aae92
  • If you're a TS users, you'll need to change import PCancelable from 'p-cancelable'; to import PCancelable = require('p-cancelable');

v1.1.0...v2.0.0