Fix dependency to uglify-js

When installing socket.io using `npm` I get an error during installation of `uglify-js`@1.2.5. This can be fixed by updating dependency to 1.2.6.

Here is the thrown error:

```
npm ERR! tar.unpack untar error /home/nchambrier/.npm/uglify-js/1.2.5/package.tgz
npm ERR! Error: ENOENT, lstat '/home/nchambrier/Bureau/formation-node/nodechat/node_modules/socket.io/node_modules/socket.io-client/node_modules/uglify-js/bin/uglifyjs'
npm ERR! If you need help, you may report this log at:
npm ERR!     <http://github.com/isaacs/npm/issues>
npm ERR! or email it to:
npm ERR!     <npm-@googlegroups.com>

npm ERR! System Linux 3.8.0-32-generic
npm ERR! command "/home/nchambrier/.nvm/v0.10.20/bin/node" "/home/nchambrier/.nvm/v0.10.20/bin/npm" "install" "socket.io"
npm ERR! cwd /home/nchambrier/Bureau/formation-node/nodechat
npm ERR! node -v v0.10.20
npm ERR! npm -v 1.3.11
npm ERR! path /home/nchambrier/Bureau/formation-node/nodechat/node_modules/socket.io/node_modules/socket.io-client/node_modules/uglify-js/bin/uglifyjs
npm ERR! fstream_path /home/nchambrier/Bureau/formation-node/nodechat/node_modules/socket.io/node_modules/socket.io-client/node_modules/uglify-js/bin/uglifyjs
npm ERR! fstream_type File
npm ERR! fstream_class FileWriter
npm ERR! code ENOENT
npm ERR! errno 34
npm ERR! fstream_stack /home/nchambrier/.nvm/v0.10.20/lib/node_modules/npm/node_modules/fstream/lib/writer.js:284:26
npm ERR! fstream_stack Object.oncomplete (fs.js:107:15)
npm ERR! error rolling back Error: ENOTEMPTY, rmdir '/home/nchambrier/Bureau/formation-node/nodechat/node_modules/socket.io/node_modules/socket.io-client/node_modules/active-x-obfuscator'
npm ERR! error rolling back  socket.io-client@0.9.16 { [Error: ENOTEMPTY, rmdir '/home/nchambrier/Bureau/formation-node/nodechat/node_modules/socket.io/node_modules/socket.io-client/node_modules/active-x-obfuscator']
npm ERR! error rolling back   errno: 53,
npm ERR! error rolling back   code: 'ENOTEMPTY',
npm ERR! error rolling back   path: '/home/nchambrier/Bureau/formation-node/nodechat/node_modules/socket.io/node_modules/socket.io-client/node_modules/active-x-obfuscator' }
npm ERR! Error: ENOENT, open '/home/nchambrier/Bureau/formation-node/nodechat/node_modules/socket.io/node_modules/socket.io-client/node_modules/ws/test/Sender.hixie.test.js'
npm ERR! If you need help, you may report this log at:
npm ERR!     <http://github.com/isaacs/npm/issues>
npm ERR! or email it to:
npm ERR!     <npm-@googlegroups.com>

npm ERR! System Linux 3.8.0-32-generic
npm ERR! command "/home/nchambrier/.nvm/v0.10.20/bin/node" "/home/nchambrier/.nvm/v0.10.20/bin/npm" "install" "socket.io"
npm ERR! cwd /home/nchambrier/Bureau/formation-node/nodechat
npm ERR! node -v v0.10.20
npm ERR! npm -v 1.3.11
npm ERR! path /home/nchambrier/Bureau/formation-node/nodechat/node_modules/socket.io/node_modules/socket.io-client/node_modules/ws/test/Sender.hixie.test.js
npm ERR! code ENOENT
npm ERR! errno 34
npm ERR! Error: ENOENT, lstat '/home/nchambrier/Bureau/formation-node/nodechat/node_modules/socket.io/node_modules/socket.io-client/node_modules/xmlhttprequest/lib/XMLHttpRequest.js'
npm ERR! If you need help, you may report this log at:
npm ERR!     <http://github.com/isaacs/npm/issues>
npm ERR! or email it to:
npm ERR!     <npm-@googlegroups.com>

npm ERR! System Linux 3.8.0-32-generic
npm ERR! command "/home/nchambrier/.nvm/v0.10.20/bin/node" "/home/nchambrier/.nvm/v0.10.20/bin/npm" "install" "socket.io"
npm ERR! cwd /home/nchambrier/Bureau/formation-node/nodechat
npm ERR! node -v v0.10.20
npm ERR! npm -v 1.3.11
npm ERR! path /home/nchambrier/Bureau/formation-node/nodechat/node_modules/socket.io/node_modules/socket.io-client/node_modules/xmlhttprequest/lib/XMLHttpRequest.js
npm ERR! fstream_path /home/nchambrier/Bureau/formation-node/nodechat/node_modules/socket.io/node_modules/socket.io-client/node_modules/xmlhttprequest/lib/XMLHttpRequest.js
npm ERR! fstream_type File
npm ERR! fstream_class FileWriter
npm ERR! code ENOENT
npm ERR! errno 34
npm ERR! fstream_stack /home/nchambrier/.nvm/v0.10.20/lib/node_modules/npm/node_modules/fstream/lib/writer.js:284:26
npm ERR! fstream_stack Object.oncomplete (fs.js:107:15)
npm http GET https://registry.npmjs.org/zeparser/0.0.5
npm ERR! Error: unexpected eof
npm ERR!     at decorate (/home/nchambrier/.nvm/v0.10.20/lib/node_modules/npm/node_modules/fstream/lib/abstract.js:67:36)
npm ERR!     at Extract.Abstract.error (/home/nchambrier/.nvm/v0.10.20/lib/node_modules/npm/node_modules/fstream/lib/abstract.js:61:12)
npm ERR!     at Extract._streamEnd (/home/nchambrier/.nvm/v0.10.20/lib/node_modules/npm/node_modules/tar/lib/extract.js:75:22)
npm ERR!     at BlockStream.<anonymous> (/home/nchambrier/.nvm/v0.10.20/lib/node_modules/npm/node_modules/tar/lib/parse.js:50:8)
npm ERR!     at BlockStream.EventEmitter.emit (events.js:92:17)
npm ERR!     at BlockStream._emitChunk (/home/nchambrier/.nvm/v0.10.20/lib/node_modules/npm/node_modules/block-stream/block-stream.js:203:10)
npm ERR!     at BlockStream.resume (/home/nchambrier/.nvm/v0.10.20/lib/node_modules/npm/node_modules/block-stream/block-stream.js:58:15)
npm ERR!     at Extract.Reader.resume (/home/nchambrier/.nvm/v0.10.20/lib/node_modules/npm/node_modules/fstream/lib/reader.js:252:34)
npm ERR!     at Entry.<anonymous> (/home/nchambrier/.nvm/v0.10.20/lib/node_modules/npm/node_modules/tar/lib/parse.js:256:8)
npm ERR!     at Entry.EventEmitter.emit (events.js:92:17)
npm ERR! If you need help, you may report this log at:
npm ERR!     <http://github.com/isaacs/npm/issues>
npm ERR! or email it to:
npm ERR!     <npm-@googlegroups.com>

npm ERR! System Linux 3.8.0-32-generic
npm ERR! command "/home/nchambrier/.nvm/v0.10.20/bin/node" "/home/nchambrier/.nvm/v0.10.20/bin/npm" "install" "socket.io"
npm ERR! cwd /home/nchambrier/Bureau/formation-node/nodechat
npm ERR! node -v v0.10.20
npm ERR! npm -v 1.3.11
npm ERR! fstream_class Extract
npm ERR! fstream_stack Extract._streamEnd (/home/nchambrier/.nvm/v0.10.20/lib/node_modules/npm/node_modules/tar/lib/extract.js:75:22)
npm ERR! fstream_stack BlockStream.<anonymous> (/home/nchambrier/.nvm/v0.10.20/lib/node_modules/npm/node_modules/tar/lib/parse.js:50:8)
npm ERR! fstream_stack BlockStream.EventEmitter.emit (events.js:92:17)
npm ERR! fstream_stack BlockStream._emitChunk (/home/nchambrier/.nvm/v0.10.20/lib/node_modules/npm/node_modules/block-stream/block-stream.js:203:10)
npm ERR! fstream_stack BlockStream.resume (/home/nchambrier/.nvm/v0.10.20/lib/node_modules/npm/node_modules/block-stream/block-stream.js:58:15)
npm ERR! fstream_stack Extract.Reader.resume (/home/nchambrier/.nvm/v0.10.20/lib/node_modules/npm/node_modules/fstream/lib/reader.js:252:34)
npm ERR! fstream_stack Entry.<anonymous> (/home/nchambrier/.nvm/v0.10.20/lib/node_modules/npm/node_modules/tar/lib/parse.js:256:8)
npm ERR! fstream_stack Entry.EventEmitter.emit (events.js:92:17)
npm http 304 https://registry.npmjs.org/zeparser/0.0.5
npm ERR! 
npm ERR! Additional logging details can be found in:
npm ERR!     /home/nchambrier/Bureau/formation-node/nodechat/npm-debug.log
npm ERR! not ok code 0
```

This is obviously an error in `uglify-js`, but it has been fixed, and it's sad we still rely on a buggy package version ;)

Note: I think `1.2.x` would be the best bet.