v4.0.0

• Merge pull request #382 from wxt2005/custom-stream 8968e01
• Fix typo e705c0a
• Merge branch 'master' of github.com:form-data/form-data into custom-stream b7b7dee
• Update README for custom stream behavior 6dd8624
• Handle custom stream a3e191d

v3.0.1...v4.0.0