Gracefully fail on Windows.

[indexzero]

I've seen this module be enough of a problem on Windows that I feel we need to either:

1. Fix it so that it works in a cross-platform way
2. Disable it on Windows and fail gracefully.

This pull-request does (2).

[3rd-Eden]

@indexzero: It would be nice know what the actual problems are before I disable it completely. As most of these bugs can probably be fixed relatively easily

[indexzero]

@3rd-Eden bash does not exist on Windows: https://github.com/observing/pre-commit/blob/master/hook

[3rd-Eden]

@indexzero it's easy enough to replace that with a bat file during the installation phase. https://github.com/observing/pre-commit/blob/master/install.js#L20

[indexzero]

@3rd-Eden absolutely. I know nothing about batch scripts so I thought disabling it for now was the best bet.

[Swaagie]

There are some more issue on windows in general though, might be good to fix those all at once ;)

[3rd-Eden]

@Swaagie so you're suggesting installing linux when installing this module ;-)?

[Swaagie]

haha

[3rd-Eden]

Fixed in #41 with a more graceful solution.