Merge pull request #73 from clouseauu/master

Ensuring executable command doesn't point to a directory

lib/tasks/bower.rake

@@ -235,7 +235,7 @@ def find_command(cmd, paths = [])
   paths.each do |path|
     exts.each do |ext|
       exe = File.join(path, "#{cmd}#{ext}")
-      return exe if File.executable? exe
+      return exe if (File.executable?(exe) && File.file?(exe))
     end
   end
   nil