Add test cases for the proxy, and do some tiny fixes.

the fixes are:
1. add "content-type" in headers for when dealing with localresponse
2. make a more accurate tip for throttle rate when lower than 1
3. make the crtMgr funcionality a more independent one
4. uppercase the request header before sending it out

update the tip

test/server/startServer.js

@@ -0,0 +1,3 @@
+const Server = require('./server.js');
+
+new Server();