Support for uploading subtitle (vtt/srt) files
Users submit a language and a label to be included with the subtitle
Includes tests
Subtitles are returned in the following format

[{
  "@id": "http://example.com/some/path/file.vtt",
  "language": "en",
  "name": "English Track"
}]
Merge pull request #24 from webnard/upload-vtt-squash

Support for uploading subtitle (vtt/srt) files