Add ability to pass sources prop to support multiple video qualities (fixes #67)

[zbuttram]

Allows the official way of adding multiple HD/SD qualities as seen here: https://support.jwplayer.com/articles/how-to-add-an-hd-quality-toggle

Also a resolution for #67

I have confirmed it works with a test build.

[ellell]

LGTM!

@danmakenoise want to take a peek at this?

[danmakenoise]

@zbuttram I'm good with it! Would you be willing to add a test for it before we merge?

[zbuttram]

@danmakenoise Yeah, no problem. Would something in the get-player-opts tests be good? Or is there somewhere we should test that its actually applying to the player?

Edit: Looks like I should add a check in shouldComponentUpdate for the sources prop as well since file and playlist are checked currently so I'll add a commit for that as well when I do the test(s).

[danmakenoise]

@zbuttram Sounds good to me, thank you!

[harsharora04]

Guys, will you be merging this anytime soon? Would really like this feature.

[zbuttram]

@harsharora04 Sorry, I imagine that's kind of on me for putting the requested changes off for so long. Just finished it up so it should be ready to merge now.

[harsharora04]

Thanks @zbuttram.

[ade1256]

Thanks, this is what i need. it worked well to me

[Cilveti]

Sources can be set now, but are a bit buggy, I'm guessing it's because this wasn't merged?
Right now if you have a playlist with multiple sources, the video resets every time you change the browser tab, which is really not ideal