build: Updating mkdirp to 0.5.3

* https://npmjs.com/advisories/1179

Additional changes:
* Enable eslint caching.

Change-Id: Ic23a9abb7647616eecdfe0c22fa39b7f0979cac5

.gitignore

@@ -5,3 +5,4 @@
 node_modules/
 /vendor
 composer.lock
+/.eslintcache

Gruntfile.js

@@ -9,7 +9,8 @@ module.exports = function ( grunt ) {
 		banana: conf.MessagesDirs,
 		eslint: {
 			options: {
-				extensions: [ '.js', '.json' ]
+				extensions: [ '.js', '.json' ],
+				cache: true
 			},
 			all: [
 				'**/*.js{,on}',

package-lock.json

@@ -1086,18 +1086,18 @@
 			}
 		},
 		"minimist": {
-			"version": "0.0.8",
+			"version": "1.2.5",
-			"resolved": "https://registry.npmjs.org/minimist/-/minimist-0.0.8.tgz",
+			"resolved": "https://registry.npmjs.org/minimist/-/minimist-1.2.5.tgz",
-			"integrity": "sha1-hX/Kv8M5fSYluCKCYuhqp6ARsF0=",
+			"integrity": "sha512-FM9nNUYrRBAELZQT3xeZQ7fmMOBg6nWNmJKTcgsJeaLstP/UODVpGsr5OhXhhXg6f+qtJ8uiZ+PUxkDWcgIXLw==",
 			"dev": true
 		},
 		"mkdirp": {
-			"version": "0.5.1",
+			"version": "0.5.3",
-			"resolved": "https://registry.npmjs.org/mkdirp/-/mkdirp-0.5.1.tgz",
+			"resolved": "https://registry.npmjs.org/mkdirp/-/mkdirp-0.5.3.tgz",
-			"integrity": "sha1-MAV0OOrGz3+MR2fzhkjWaX11yQM=",
+			"integrity": "sha512-P+2gwrFqx8lhew375MQHHeTlY8AuOJSrGf0R5ddkEndUkmwpgUob/vQuBD1V22/Cw1/lJr4x+EjllSezBThzBg==",
 			"dev": true,
 			"requires": {
-				"minimist": "0.0.8"
+				"minimist": "^1.2.5"
 			}
 		},
 		"ms": {