upgrade VIM / finalize package

[erichiller]

Currently vim must be manually upgraded. I've made this as easy as possible with omega.vimrc and vim.cmd so that upgrading is simply placing the upgraded binaries into system/.

The majority of a package-type setup is in place, may as well finish it.

Currently it is built to use a custom .json meta file and download some arbitrary data.

Increasingly though I think it would be better to use PowerShell's already existing module system.

Auto-updates could be performed using ConEmu's existing updater (it is highly configurable)

#2

https://trello.com/c/RERIFzMn