Fix hardcoded reference to ruby1.8

This resolves bug 2899

Signed-off-by: François Andriot <francois.andriot@free.fr>
(cherry picked from commit 2edeeb061c)

qtruby/bin/rbqtapi

@@ -1,4 +1,4 @@
-#!/usr/bin/env ruby1.8
+#!/usr/bin/env ruby
 
 # Note: this program is part of qtruby and makes use of its internal functions.
 #       You should not rely on those in your own programs.

qtruby/bin/rbqtsh

@@ -1,4 +1,4 @@
-#!/usr/bin/env ruby1.8
+#!/usr/bin/env ruby
 
 # rbqtsh : a graphical shell for qtruby.
 #