rakefile: avoid doing the syntaxcheck on vendor dir

Looks like travis installs all gems to the vendor dir,
that means that the syntaxcheck will check all the ruby files
under that directory, slowing down the travis work for no reason.

This removes any rb files coming from under the vendor directory

Rakefile

@@ -103,7 +103,7 @@ unless ENV["PACKAGING"] && ENV["PACKAGING"] == "yes"
   RSpec::Core::RakeTask.new(:spec)
 
   task :syntaxcheck do
-    system("for f in `find -name \*.rb`; do echo -n \"Syntaxcheck $f: \"; ruby -wc $f || exit $? ; done")
+    system("for f in `find -not -path './vendor*' -name \*.rb`; do echo -n \"Syntaxcheck $f: \"; ruby -wc $f || exit $? ; done")
     exit $?.exitstatus
   end