fix: .snyk & package.json to reduce vulnerabilities

The following vulnerabilities are fixed with a Snyk patch:
- https://snyk.io/vuln/npm:hoek:20180212

.snyk

@@ -0,0 +1,10 @@
+# Snyk (https://snyk.io) policy file, patches or ignores known vulnerabilities.
+version: v1.12.0
+ignore: {}
+# patches apply the minimum changes required to fix a vulnerability
+patch:
+  'npm:hoek:20180212':
+    - nexmo > jsonwebtoken > joi > hoek:
+        patched: '2018-06-21T06:47:31.937Z'
+    - nexmo > jsonwebtoken > joi > topo > hoek:
+        patched: '2018-06-21T06:47:31.937Z'

package.json

@@ -8,10 +8,13 @@
     "node": ">=4.0.0"
   },
   "scripts": {
-    "test": "lab -c -v -L -a code"
+    "test": "lab -c -v -L -a code",
+    "snyk-protect": "snyk protect",
+    "prepare": "npm run snyk-protect"
   },
   "dependencies": {
-    "nexmo": "2.1.x"
+    "nexmo": "2.1.x",
+    "snyk": "^1.83.0"
   },
   "devDependencies": {
     "hapi": ">=17.2.x",
@@ -20,5 +23,6 @@
     "lab": "15.1.x",
     "nexmo": "2.1.x",
     "coveralls": "3.0.x"
-  }
+  },
+  "snyk": true
 }