Support for Coub

[davidmz]

Please, add Coub suport. From oembed.com:

Coub (http://coub.com/)
  URL scheme: http://coub.com/view/*
  URL scheme: http://coub.com/embed/*
  API endpoint: http://coub.com/api/oembed.{format}

  Example: http://coub.com/api/oembed.xml?url=http://coub.com/view/um0um0
  Example: http://coub.com/api/oembed.json?url=http://coub.com/view/um0um0
  Example: http://coub.com/api/oembed.xml?url=http://coub.com/embed/um0um0
  Example: http://coub.com/api/oembed.json?url=http://coub.com/embed/um0um0

[leedo]

I've updated noembed to pull the default provider list from oembed.com, so this is now supported.