Component should only update if a player exists

[Jackdupkevin]

This PR will...

• In shouldComponentUpdate() we are checking if the player exists, and will then update event listeners. Currently event listeners are being updated before a player exists and that causes errors.

Why is this Pull Request needed?

• Currently the player is not usable with on<Event> listeners.

Are there any points in the code the reviewer needs to double check?

Are there any Pull Requests open in other repos which need to be merged with this?

• No

Addresses Issue(s):

• window.jwplayer(...).setup is not a function #12

[jwplayer-robot]

Can one of the admins verify this patch?

[mdaoust-sidlee]

Interested to know when this PR will get published, thanks in advance.

[gsinovsky]

@imbcmdth could we please get this PR approved and merged? thanks!

[derweili]

From what I can see here, this also fixes #17

@imbcmdth @mamaddox
As you are the ones how have most commits on this repo so assuming you are admins, could you review and potentially merge this PR?

[mamaddox]

Sorry for the delay and great catch! We'll try to get this out next week. I'll ping you all when it gets in.

[bcole2433]

Will this be pushed to the yarn package soon?

[mamaddox]

Hey everyone, we've just published a new version on npm. Let me know if you have any issues.