As of late 2016, is config considered to be a word in proper English, as opposed to a slang shorthand (verbal and written)?

The reason it may be is that it is used all the time, particularly in software development and configuration. The reason it may not be is that it is not prone to showing up in dictionaries. While the latter makes a strong case against it, if a word is commonly used and accepted in official writings, it could still be regarded academically as correct and proper, with only a few particular organizations having yet to give their internal stamps of approval.