Shift+Tab processing

Shift+Tab must works not as Tab but in reverse direction, as Esc.

P.S. This patch is **untested**. Please test it yourself.

I can not test this patch: first time server ran and said
```
Error: ENOENT, stat 'index.html'
```
now server does not start at all:
```
Model loaded TodoList  at  /home/as/prg/js/todomvc-swarm/model/TodoList.js
Model loaded TodoItem  at  /home/as/prg/js/todomvc-swarm/model/TodoItem.js
uncaught: [Error: Unknown encoding] Error: Unknown encoding
    at Buffer.toString (buffer.js:434:13)
    at Object.fs.readFileSync (fs.js:236:33)
    at Storage.FileStorage.loadLog (/home/as/node_modules/swarm/lib/FileStorage.js:159:19)
    at Storage.FileStorage (/home/as/node_modules/swarm/lib/FileStorage.js:29:10)
    at Object.<anonymous> (/home/as/prg/js/todomvc-swarm/serv.js:41:19)
    at Module._compile (module.js:449:26)
    at Object.Module._extensions..js (module.js:467:10)
    at Module.load (module.js:356:32)
    at Function.Module._load (module.js:312:12)
    at Module.runMain (module.js:492:10)
```