Discontinuities with encryption

[biddster]

This library is fantastic and I'm using it to merge playlists. However, some of our segments are encrypted and we specify an EXT-X-KEY in the m3u8. When concatenating the playlists, only the first playlist has the EXT-X-KEY preserved.

A good example of what we're doing is here in the apple docs. https://developer.apple.com/library/ios/technotes/tn2288/_index.html#//apple_ref/doc/uid/DTS40012238-CH1-ENCRYPT

[bog]

I'd accept a PR for this.