Check real fs case sensitivity

[koroandr]

Fix for #200

I used fs-file-name-sensitive module to check the case sensitivity on some file (__filename in Host.js). It simply checks, if we change filename to upper case, would it be opened.

The solution is not so elegant, but works fine for me.

[cartant]

I'm closing this, as I've merged a change that should detect case sensitivity without using the fs-file-name-sensitive module. I'd prefer not to add a dependency unless absolutely necessary and I'm not especially keen on that module's implementation, as it creates and removes a temporary file.

If you could verify that the current master solves your problem, I'll publish a new version to NPM.