Adding nsp check to the build process

[hairyhenderson]

Recently there've been a few security vulnerabilities discovered in dependencies of engine.io (such as #401 and #410, among others).

This PR adds an nsp check to the test process, such that when the gulp test command is run, engine.io's dependencies are scanned for vulnerabilities by nsp.

This way, the build will fail immediately when there's a vulnerable dependency, making it obvious that the dependency's version needs updating.

Signed-off-by: Dave Henderson dhenderson@gmail.com

[hairyhenderson]

So, that travis failure is kind of a good indication that this is working 😉

[18:47:37] Using gulpfile ~/build/socketio/engine.io/gulpfile.js
[18:47:37] Starting 'nsp'...
[18:47:37] 'nsp' errored after 225 ms
[18:47:37] Error in plugin 'gulp-nsp'
Message:
    (+) 1 vulnerabilities found
┌───────────────┬───────────────────────────────────────────────────────┐
│               │ DoS due to excessively large websocket message        │
├───────────────┼───────────────────────────────────────────────────────┤
│ Name          │ ws                                                    │
├───────────────┼───────────────────────────────────────────────────────┤
│ Installed     │ 1.1.0                                                 │
├───────────────┼───────────────────────────────────────────────────────┤
│ Vulnerable    │ <=1.1.0                                               │
├───────────────┼───────────────────────────────────────────────────────┤
│ Patched       │ >=1.1.1                                               │
├───────────────┼───────────────────────────────────────────────────────┤
│ Path          │ engine.io@1.6.11 > ws@1.1.0                           │
├───────────────┼───────────────────────────────────────────────────────┤
│ More Info     │ https://nodesecurity.io/advisories/120                │
└───────────────┴───────────────────────────────────────────────────────┘

Guess I'll update the ws dep here too so this passes...

[darrachequesne]

Thanks!