Add ability to ignore directories.

[rsenk330]

This is helpful when there are large directories with static assets that don't need to be watched.

It could probably be easily expanded to support regular expressions, but wanted to get your feedback first before doing too much.

[codegangsta]

looks like the build failed but it must have been a blip. Rerunning

[rsenk330]

I think the tests failing was a blip. I rebased on the current master, and everything seems good now.

Can you think of a better way to handle this? I'm willing to make this more robust if needed.

[platinumthinker]

I not sure but this PR does not duplicate flags --excludeDir value, -x value ?