Add Guardfile for continuious testing

Guardfile

@@ -0,0 +1,9 @@
+# A sample Guardfile
+# More info at https://github.com/guard/guard#readme
+
+# Add files and commands to this file, like the example:
+#   watch(%r{file/path}) { `command(s)` }
+#
+guard 'go', test: true, server: 'cpu.go' do
+  watch(%r{\.go$})
+end