Prevent stopping server when sass has error.

[azemoh]

This prevents browser-sync from stopping when sass has errors. It just prints the error and server keeps running.

[Sandstedt]

Works great! You could also keep the browserSync notification, like this:

.pipe(sass({
    includePaths: ['scss'],
    onError: browserSync.notify('Error in sass')
}))
.on('error', sass.logError)

[azemoh]

That's right, I see why it stops the server. Made changes in PR #51