How do I block Semalt.com and buttons-for-websites.com from spamming my analytics?

Looking at my recent analytics I noticed an increase in foreign visits to my website.  Upon further review I find the referrer is buttons-for-websites.com.  Evidently this is a spam referrer that can skew your analytics and they also are able to look or find a list of referrers from this spam.  How do we block them through Homestead?  I know there is a way to do it through Google, but dont know if it would be effective to Homestead. Anyone have answers?