fix: package.json to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/npm:cryptiles:20180710
- https://snyk.io/vuln/npm:extend:20180424
- https://snyk.io/vuln/npm:hoek:20180212
- https://snyk.io/vuln/npm:lodash:20180130
- https://snyk.io/vuln/npm:sshpk:20180409
- https://snyk.io/vuln/npm:stringstream:20180511

package.json

@@ -44,6 +44,6 @@
   "dependencies": {
     "hlsdownloader": "^2.1.0",
     "minimist": "^1.2.0",
-    "request": "^2.83.0"
+    "request": "^2.84.0"
   }
 }