Add travis_config.rb

travis_config.rb

+MRuby::Build.new do |conf|
+  toolchain :gcc
+
+
+  conf.gem "#{root}/mrbgems/mruby-sprintf"
+  conf.gem "#{root}/mrbgems/mruby-print"
+
+  Dir.glob("#{root}/mrbgems/mruby-*") do |x|
+    conf.gem x unless x =~ /\/mruby-(print|sprintf)$/
+  end
+end