Feature/mp4

[gpenverne]

• Added get_mp4_status() method on File (cf )
• Added ask_for_mp4() method on File (cf )
• Added parameter "prefer_mp4" on get_stream_link, which return mp4 if available

[gpenverne]

;) @cenkalti ?

[cenkalti]

Thanks @gpenverne. I have made some changes over your PR to keep this library simple. I suggest you to add extra logic to your application code.

You can download the new version with pip install -U putio.py