Re-write mediawiki-vagrant

* Use official Ubuntu vagrant images, provided by Canonical
* Use v2 of Vagrantfile spec
* Configure MediaWiki for development (debug logs, profiling, etc.)
* Use host-only networking
* Bump memory size to 512MB
* Auto-detect NFS support and use it if available.
* Specify resource defaults
* Move modules and manifests to ./puppet
* Consolidate interdependent classes into 'mediawiki' module
* Follow Puppet's style guide
* Run 'apt-get update', but no more than once every 24 hours.
* Update MOTD to remove Canonical plugs and replace with ASCII banner and links
  to documentation.
* Add class for git-cloning MediaWiki (present but not used.)
* Add class for fetching MediaWiki snapshot from GitHub.
* Parametrize classes
* Use mod_alias and mod_rewrite in Apache configs; closely mirrors prod.
* Use descriptive name for puppet resources
* Generate ctags for phpsh
* Allow vanilla codebase mode in rc.php (phpsh)
* Remove MediaWiki submodule; fetch MediaWiki snapshot from GitHub
* Use default port for Memcached
* Updated logo URL to point to commons.
* ..lots of other stuff I can't remember.

Git best-practices be damned; I ain't splitting this one up.

TODO: Ensure appropriate version of VirtualBox Guest Additions are
installed.

Change-Id: Ide918954bc469249b50f7d06a0529fd5cfe05307