Added type to content source

[jascaldeira]

Resolved an issue with IMA plugin and HLS plugin on post-roll completed ads: without the source type the player hangs with a format not supported error.

Originally solved in old IMA plugin version by @valse:
#433

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[jascaldeira]

I signed it!

[googlebot]

CLAs look good, thanks!

[shawnbuso]

lint says you're missing a trailing comma here - other than that, looks good to me!

[shawnbuso]

Sorry for the long delay here - I couldn't figure out why those tests are failing, and I finally found it - this needs to be this.vjsPlayer.currentType() instead of this.player.currentType()