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.
@greg80303, I don't know, I haven't seen it used either. I only kept it because it's what was there already, to not break any possible implementation I haven't seen but yeah, normally, "setMediaKeys" would probably be used by all non-prefixed API's.