Adding variable to extend the ack with additional default params.

[jswartwood]

By setting g:ackargs, one can now add additional defaults to :Ack within Vim. I use ack on command line for many things, but commonly have a default set of additional ack args for projects. For example, I've added this to my .vimrc.

" Better than grep
let g:ackargs="--ignore-dir=build\\ --ignore-dir=min"

I'm a little green to vim scripting, so it is entirely possible that there is a much better way to do this.