fix documentation

ag is a replacement for ack, not itself
Merge pull request #6 from joshuarh/fix-documentation

fix documentation
Fix command.
Merge pull request #7 from wiredool/fix-command

Fix command.
'rake tgz' for deploying to vim.org
Added Vundle install notes
Merge pull request #8 from paulyoder/patch-1

Added Vundle install notes
Install commands fixups

- Making the package install command work, updating now that I know Ubuntu doesn't have it by default (yet?)
- Spiffing up the vim ones so they're more one-linery