Minor gemspec fixups
Minor gemspec fixups

The `test_files` gemspec option seems to be pretty obsolete. I also
updated the homepage URL.

ngpestelos/pry,icebreaker/pry,printercu/pry,geoffreylitt/pry,tdg5/pry,85x14/pry,jasnow/pry,raeno/pry,raeno/pry,tdg5/pry,shockone/pry,ooohiroyukiooo/pry,caporta/pry,nju520/pry,nju520/pry,ngpestelos/pry,scalixte-mdsol/pry,jasnow/pry,jasonm23/pry,scalixte-mdsol/pry,nju520/pry,sferik/pry,shockone/pry,ooohiroyukiooo/pry,85x14/pry,scalixte-mdsol/pry,jasonm23/pry,gfvcastro/pry,caporta/pry,shockone/pry,geoffreylitt/pry,jasnow/pry,printercu/pry,raeno/pry,josue804/debunker,tdg5/pry,sideci-sample/sideci-sample-pry,caporta/pry,jasonm23/pry,bronzdoc/pry,icebreaker/pry,ooohiroyukiooo/pry,pvdb/pry,85x14/pry,sferik/pry,josue804/debunker,pvdb/pry,gfvcastro/pry,bronzdoc/pry