fix: package.json, package-lock.json & .snyk to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JS-JSYAML-173999
- https://snyk.io/vuln/SNYK-JS-JSYAML-174129
- https://snyk.io/vuln/SNYK-JS-NODESASS-535499
- https://snyk.io/vuln/SNYK-JS-NODESASS-535500
- https://snyk.io/vuln/SNYK-JS-NODESASS-535501
- https://snyk.io/vuln/SNYK-JS-NODESASS-535503
- https://snyk.io/vuln/SNYK-JS-NODESASS-535504
- https://snyk.io/vuln/SNYK-JS-NODESASS-535505
- https://snyk.io/vuln/SNYK-JS-NODESASS-540960
- https://snyk.io/vuln/SNYK-JS-NODESASS-540962
- https://snyk.io/vuln/SNYK-JS-NODESASS-540966
- https://snyk.io/vuln/SNYK-JS-NODESASS-540968
- https://snyk.io/vuln/SNYK-JS-NODESASS-540970
- https://snyk.io/vuln/SNYK-JS-NODESASS-540972
- https://snyk.io/vuln/SNYK-JS-NODESASS-540982
- https://snyk.io/vuln/SNYK-JS-NODESASS-540984
- https://snyk.io/vuln/SNYK-JS-NODESASS-540986
- https://snyk.io/vuln/SNYK-JS-NODESASS-540988
- https://snyk.io/vuln/SNYK-JS-NODESASS-542662
- https://snyk.io/vuln/npm:debug:20170905
- https://snyk.io/vuln/npm:fresh:20170908
- https://snyk.io/vuln/npm:mime:20170907
- https://snyk.io/vuln/npm:ms:20170412
- https://snyk.io/vuln/npm:qs:20170213


The following vulnerabilities are fixed with a Snyk patch:
- https://snyk.io/vuln/SNYK-JS-LODASH-567746
- https://snyk.io/vuln/npm:debug:20170905
- https://snyk.io/vuln/npm:extend:20180424
- https://snyk.io/vuln/npm:hoek:20180212
- https://snyk.io/vuln/npm:ms:20170412
- https://snyk.io/vuln/npm:stringstream:20180511

.snyk

@@ -0,0 +1,47 @@
+# Snyk (https://snyk.io) policy file, patches or ignores known vulnerabilities.
+version: v1.14.1
+ignore: {}
+# patches apply the minimum changes required to fix a vulnerability
+patch:
+  'npm:debug:20170905':
+    - gulp-connect > tiny-lr > body-parser > debug:
+        patched: '2020-05-27T08:37:47.510Z'
+  'npm:extend:20180424':
+    - gulp > gulp-cli > liftoff > extend:
+        patched: '2020-05-27T08:37:47.510Z'
+    - gulp > vinyl-fs > glob-stream > extend:
+        patched: '2020-05-27T08:37:47.510Z'
+    - gulp-sass > node-sass > request > extend:
+        patched: '2020-05-27T08:37:47.510Z'
+    - gulp-sass > node-sass > node-gyp > request > extend:
+        patched: '2020-05-27T08:37:47.510Z'
+  'npm:hoek:20180212':
+    - gulp-sass > node-sass > request > hawk > hoek:
+        patched: '2020-05-27T08:37:47.510Z'
+    - gulp-sass > node-sass > request > hawk > boom > hoek:
+        patched: '2020-05-27T08:37:47.510Z'
+    - gulp-sass > node-sass > request > hawk > sntp > hoek:
+        patched: '2020-05-27T08:37:47.510Z'
+    - gulp-sass > node-sass > node-gyp > request > hawk > hoek:
+        patched: '2020-05-27T08:37:47.510Z'
+    - gulp-sass > node-sass > node-gyp > request > hawk > boom > hoek:
+        patched: '2020-05-27T08:37:47.510Z'
+    - gulp-sass > node-sass > request > hawk > cryptiles > boom > hoek:
+        patched: '2020-05-27T08:37:47.510Z'
+    - gulp-sass > node-sass > node-gyp > request > hawk > sntp > hoek:
+        patched: '2020-05-27T08:37:47.510Z'
+    - gulp-sass > node-sass > node-gyp > request > hawk > cryptiles > boom > hoek:
+        patched: '2020-05-27T08:37:47.510Z'
+  SNYK-JS-LODASH-567746:
+    - gulp-sass > node-sass > sass-graph > lodash:
+        patched: '2020-05-27T08:37:47.510Z'
+    - gulp-sass > node-sass > gaze > globule > lodash:
+        patched: '2020-05-27T08:37:47.510Z'
+  'npm:ms:20170412':
+    - gulp-connect > tiny-lr > body-parser > debug > ms:
+        patched: '2020-05-27T08:37:47.510Z'
+  'npm:stringstream:20180511':
+    - gulp-sass > node-sass > request > stringstream:
+        patched: '2020-05-27T08:37:47.510Z'
+    - gulp-sass > node-sass > node-gyp > request > stringstream:
+        patched: '2020-05-27T08:37:47.510Z'