hub: fix hardcoded ruby path
hub: fix hardcoded ruby path

rake hardcoded the path to ruby in the installed scripts, which breaks
the script when ruby is updated. Just use #!ruby for Haiku, as this
works fine and resists updates.

miqlas/haikuports,nielx/haikuports,koletzky/haikuports,nielx/haikuports,Begasus/haikuports,moochris/haikuports,haikuports/haikuports,koletzky/haikuports,koletzky/haikuports,Begasus/haikuports,Begasus/haikuports,Begasus/haikuports,haikuports/haikuports,miqlas/haikuports,Begasus/haikuports,moochris/haikuports,miqlas/haikuports,haikuports/haikuports,haikuports/haikuports,nielx/haikuports,haikuports/haikuports,moochris/haikuports