add diskusage monitor

package-lock.json

@@ -229,6 +229,15 @@
         "kuler": "1.0.x"
       }
     },
+    "diskusage": {
+      "version": "1.0.0",
+      "resolved": "https://registry.npmjs.org/diskusage/-/diskusage-1.0.0.tgz",
+      "integrity": "sha512-eOrPVSZLxo8kXz03GA+gdKauSSmicNET/pXMZKXs1vkdZrEayeZmJYu1Eo2uzVhkQL748vq1irIi7hzoPWBRmQ==",
+      "requires": {
+        "es6-promise": "^4.2.5",
+        "nan": "^2.11.1"
+      }
+    },
     "ecc-jsbn": {
       "version": "0.1.2",
       "resolved": "https://registry.npmjs.org/ecc-jsbn/-/ecc-jsbn-0.1.2.tgz",
@@ -251,6 +260,11 @@
       "resolved": "https://registry.npmjs.org/env-variable/-/env-variable-0.0.5.tgz",
       "integrity": "sha512-zoB603vQReOFvTg5xMl9I1P2PnHsHQQKTEowsKKD7nseUfJq6UWzK+4YtlWUO1nhiQUxe6XMkk+JleSZD1NZFA=="
     },
+    "es6-promise": {
+      "version": "4.2.5",
+      "resolved": "https://registry.npmjs.org/es6-promise/-/es6-promise-4.2.5.tgz",
+      "integrity": "sha512-n6wvpdE43VFtJq+lUDYDBFUwV8TZbuGXLV4D6wKafg13ldznKsyEvatubnmUe31zcvelSzOHF+XbaT+Bl9ObDg=="
+    },
     "escape-string-regexp": {
       "version": "1.0.5",
       "resolved": "https://registry.npmjs.org/escape-string-regexp/-/escape-string-regexp-1.0.5.tgz",
@@ -505,6 +519,11 @@
         "tedious": "^2.7.1"
       }
     },
+    "nan": {
+      "version": "2.12.1",
+      "resolved": "https://registry.npmjs.org/nan/-/nan-2.12.1.tgz",
+      "integrity": "sha512-JY7V6lRkStKcKTvHO5NVSQRv+RV+FIL5pvDoLiAtSL9pKlC5x9PKQcZDsq7m4FO4d57mkhC6Z+QhAh3Jdk5JFw=="
+    },
     "native-duplexpair": {
       "version": "1.0.0",
       "resolved": "https://registry.npmjs.org/native-duplexpair/-/native-duplexpair-1.0.0.tgz",