Use ruby 1.8-compatible call syntax for Kernel#system (issue #17)

lib/qwandry/configuration.rb

@@ -23,7 +23,7 @@ module Qwandry
       
       # Returns true if binary `name` is present.
       def present? name
-        system("which #{name}", STDOUT=>"/dev/null")
+        system("which #{name} > /dev/null")
       end
       
       # Sets the default configuration to launch, if no `configurations` are passed
@@ -144,4 +144,4 @@ module Qwandry
     end
     
   end
-end
+end