fix #7, which contains 2 div element with same id;
make the name of file more impressive;
add activation of client side in ssr;
add compiler config of client side in ssr;

Change

see above

Does this PR introduce a breaking change?

no

What needs to be documented once your changes are merged?

npm run pressr-client will compiled ssr-client.js, and the compiled file is used to finish the activation of ssr rendering according to vue official intro. Then, you can use vue-router or vuex in ssr.
npm run pressr-server will compiled App.js, and the compiled file will be required in server.js, rendered to string by createSSRApp, then response this string to browser.
If your want to see the effect quickly, run npm run pressr, then run npm run ssr

Additional Comments