Improve the installation and update mechanism

[danielbachhuber]

Users currently have to download a ZIP, extract, and require the command file in order to use one of the premium commands. We should make this process much more seamless.

[danielbachhuber]

Looks like it's relatively easy to set up a private Composer instance https://getcomposer.org/doc/articles/handling-private-packages-with-satis.md