Key Authorization

Created by: osbornjd

This PR introduces a key authorization feature that allows users to authorize their remote commands and file handles via a provided key. There are also some additions to the authorization structure, such as a BasicConnectionAuthorizationHandler which allows users to just provide their username, hostname, and password if they like and are willing to assume the risks of storing the password briefly in memory. Note that there are several comments warning users of this risk, in addition to there being already better implemented ways of password handling.

All other changes are either formatting the code (i.e. deleting unnecessary white space) or fixing some small straggling "TODOs" that remained.