Comparison of distribution options

This is a comparison of different options in distributing MediaWiki, with some pros and cons and notes about extension support for each. There's been some discussion about which distribution strategy we should pick, but I (Legoktm) have come to the conclusion that we should try to support as many as we can do a good job for, and let people use MW in the way that they prefer.

Release tarballs
Pros: Cons: Extension support:
 * Officially supported by MediaWiki developers and WMF Release Engineering Team
 * Doesn't require knowledge of CLI
 * Composer dependencies are bundled so you don't need to use composer
 * Popular extensions and skins are bundled so those don't need to be downloaded separately
 * A set of stable, reviewed, and popular extensions and skins are bundled with the tarball
 * Extensions/skins hosted on Gerrit get individual tarballs via ExtensionDistributor

Git
Pros: Cons: Extension support:
 * Officially supported by MediaWiki developers and WMF Release Engineering Team
 * Used by all developers (at least master is)
 * Easy to cherry-pick bug fixes that don't get backported, or upgrade to changes merged in a release branch but not yet released officially
 * Composer dependencies are not included and must be downloaded separately (via composer or git)
 * Skins are separate and need to be downloaded separately
 * Any extension managed in a git repo can be used

Debian package
Pros: Cons: Extension support:
 * Easy as
 * Present in modern Debian/Ubuntu releases already
 * Requires root access to install
 * Differs from the normal MediaWiki filesystem layout
 * Currently only supports those extensions bundled with the tarball

Docker
I don't know anything about this yet, someone else should fill this out

MediaWiki-Vagrant
Pros: Cons: Extension support:
 * Used by many developers
 * Uses puppet for automation, automatically sets up developer environment
 * Supports multiversion, aims to come close to Wikimedia production
 * Easy to deploy to Wikimedia Labs
 * Intended for developers, not suitable for production
 * Requires VM or lxc to work
 * Extensions need to have their "roles" committed to the MediaWiki-Vagrant git repository to work