Update singleURLfetch.py

Rather than parse URLs i search for double slashes in anchor tags' href arguments. I know i'll hate myself later if i don't comment this so here's this. string.partition will split a string into a tuple based on 1 argument, a separator. in this case, i use double slashes '//' the resulting tuple will have empty [1] and [2] indices. I then verify that one of the first two chars of the URI is a forward slash.
As of now this rejects self-referencing links ("https://github.com/genewitch/ephasia/edit/master/singleURLfetch.py"), mailto, and another weird glitch.