Release v0.9.1

[hahwul]

Summary

• Fixed nil-cast bug in oas2,oas3,raml analyzers (Unhandled exception: Cast from Nil to Hash(K, V) failed #126)
  • Add test code for nil-cast issue (functional_test/fixtures/oas3/nil_cast/)
  • Improve debug logs
• Fixed bug in js-express (Unhandled exception: Cast from Nil to Hash(K, V) failed #126)
• Fixed typo in Deliver initialize (Customer headers strips the character 's' #132)
  • Add test code for header in deliver