add support for application/json content type requests
Merge branch 'master' into pr/686

* master: (62 commits)
  build_nested_query includes integer values
  Rack::ETag correctly marks etags as Weak
  Fix yet another body close bug in Rack::Deflater
  Implement full Logger interface on NullLogger
  Revert "support empty string multipart filename"
  support empty string multipart filename
  multipart/form-data with files with no input name
  Fix parent type API regression introduced in #713
  correct weird case regression from #714
  UrlMap: Enable case-insensitive domain matching
  Raise specific exception if the parameters are invalid
  Fix media_type_params when Content-Type parameters contains quoted-strings
  Rack::Multipart::UploadedFile has file extensions
  multipart content-type match now case insensitive
  Undo test that falsely exemplifies production env
  default_middleware_by_environment should always returns empty array for unknown keys
  Remove rbx from Travis' allow_failures
  Fix rbx settings for Travis
  Use latest 2.1 on Travis
  Enable cleanup of Tempfiles from multipart form data by default
  ...

Conflicts:
	lib/rack/request.rb
Merge branch 'pr/686'

* pr/686:
  add support for application/json content type requests