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 +1,22 @@
+# 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':
+    - '@rails/webpacker > node-sass > request > hawk > hoek':
+        patched: '2018-06-19T06:37:40.039Z'
+    - '@rails/webpacker > node-sass > request > hawk > boom > hoek':
+        patched: '2018-06-19T06:37:40.039Z'
+    - '@rails/webpacker > node-sass > request > hawk > sntp > hoek':
+        patched: '2018-06-19T06:37:40.039Z'
+    - '@rails/webpacker > node-sass > request > hawk > cryptiles > boom > hoek':
+        patched: '2018-06-19T06:37:40.039Z'
+    - '@rails/webpacker > node-sass > node-gyp > request > hawk > hoek':
+        patched: '2018-06-19T06:37:40.039Z'
+    - '@rails/webpacker > node-sass > node-gyp > request > hawk > boom > hoek':
+        patched: '2018-06-19T06:37:40.039Z'
+    - '@rails/webpacker > node-sass > node-gyp > request > hawk > sntp > hoek':
+        patched: '2018-06-19T06:37:40.039Z'
+    - '@rails/webpacker > node-sass > node-gyp > request > hawk > cryptiles > boom > hoek':
+        patched: '2018-06-19T06:37:40.039Z'

package.json

@@ -2,13 +2,19 @@
   "dependencies": {
     "@rails/webpacker": "^3.4.3",
     "google-maps-infobox": "^2.0.0",
-    "rails-erb-loader": "^5.2.1"
+    "rails-erb-loader": "^5.2.1",
+    "snyk": "^1.83.0"
   },
   "devDependencies": {
     "babel-eslint": "^7.2.3",
     "eslint": "^3.19.0",
     "eslint-config-airbnb-base": "^11.2.0",
     "eslint-plugin-import": "^2.2.0",
     "webpack-dev-server": "^2.11.1"
-  }
+  },
+  "scripts": {
+    "snyk-protect": "snyk protect",
+    "prepare": "npm run snyk-protect"
+  },
+  "snyk": true
 }