Reduce loopback aliases to 5

The high number of interfaces causes Mac OS X ntpd runs out of open
files and fails to start. launchd will then try over and over every 10
seconds, resulting in massive log spam.
Add a new directory alias
Don't use relative line numbering in vim

* It doesn't always kick in, for some reason.
* When it does work, seeing numbers jump around is quite distracting.
Ignore all .DS_Store files (boo, OS X!)
Add vim-bundler package