Preferred quality as argument

[raakatz]

Is your feature request related to a problem? Please describe. Can't download other qualities than 192 since it's hardcoded in the youtube.py file

Describe the solution you'd like An additional argument such as --preferred_quality that takes a parameter and passes it as a variable to the relevant functions

Opened PR at https://github.com/SathyaBhat/spotify-dl/pull/361