Allow empty string as slug separator

[samnabi]

Right now, the str::slug() method doesn't allow an empty string as a separator. It would be good to modify this function to differentiate between NULL and '', and allow the empty string as a separator.

Right now I'm using this function to achieve the effect: str_replace('-', '', str::slug($string))

[bastianallgeier]

I just implemented this on the develop branch.

[samnabi]

Thanks!