Resubmit: Adding support for Widevine (merged changes by @colde)

* Adding Widevine support.
* Extending PlayReady support with optional CustomData.
* Adding option to override protectionData (including laUrl, cdmData &
license request headers) when instantiating the player.
* Moved parsing of CDM message into respective DRM license acquirers.
Hi @Hyddan ,
I've been testing this PR and always get a laUrl = null at this point. Passing protectionData instead, it works.
I think the problem comes from ProtectionModel.js:108:
* keySystems[kid].keySystem.laUrl() = null
* event.destinationURL = undefined

Are you able to reproduce the same problem?

Thanks.