Limit the language in a VMR

[marcos-cereijo-pexip]

Right now we display the whole list of languages in the language selector. The idea is to implement a way to only display a subset of them.

What we discussed is to define the list of available languages in the VMR description. The format of this parameter should be something similar to these:

spanish, english, french

If the description is empty or it doesn't match any language, display the whole list of languages.