feat(deps): remove nsp dev dependency

The NSP service is shutting down, and as far as I know we have not used
this tool frequently at all. NPM has better tools built in now, like
`npm audit`.

package.json

@@ -8,7 +8,6 @@
   "main": "index.js",
   "bin": "./bin/start",
   "scripts": {
-    "audit": "npm shrinkwrap; node node_modules/nsp/bin/nsp check; rm npm-shrinkwrap.json;",
     "ciao": "node node_modules/ciao/bin/ciao -c test/ciao.json test/ciao",
     "coverage": "node_modules/.bin/istanbul cover test/unit/run.js",
     "docs": "./bin/generate-docs",
@@ -71,7 +70,6 @@
     "difflet": "^1.0.1",
     "istanbul": "^0.4.2",
     "jshint": "^2.5.6",
-    "nsp": "^3.0.0",
     "pelias-mock-logger": "^1.3.0",
     "precommit-hook": "^3.0.0",
     "proxyquire": "^2.0.0",