Parse Bitrate value as integer not string

[davemevans]

See #376.

Would break people who are doing data["segments"][0]["bitrate"] == "1674" (which is the intention), because we wish bitrate to be int.

Would also break people who are doing obj.segments[0].bitrate = "9876" because dumps explicitly requires int now, which I think is fine but could be changed to be more lenient.

[mauricioabreu]

Thank you @davemevans nice fix.

Since it breaks users of m3u8, I'm going to release a major version again.