Upgrading npm dependencies with ciritical vulnerabililities (#103)

* Upgrading two npm packages which contained critical vulnerabilities.

* Upgrading webpack. 

* Setting ajv-keywords and ajv versions for version resolution. 

* Adding required webpack-cli to dependencies as its required by the latest version of webpack. 

* Pinning node version to be the latest LTS.

build.gradle

@@ -139,6 +139,7 @@ project(':ui') {
   apply plugin: 'com.moowork.node'
   node {
     download = true
+    version = '12.14.1'
   }
 
   task test_(type: NpmTask, overwrite: true) {

ui/package.json

@@ -15,6 +15,8 @@
     "react-router-dom": "^4.2.2"
   },
   "devDependencies": {
+    "ajv": "^6.10.2",
+    "ajv-keywords": "^3.4.1",
     "babel-core": "^6.26.0",
     "babel-eslint": "^7.2.3",
     "babel-jest": "^21.2.0",
@@ -23,7 +25,7 @@
     "babel-plugin-transform-react-jsx": "^6.24.1",
     "babel-preset-es2015": "^6.24.1",
     "babel-preset-react": "^6.24.1",
-    "css-loader": "^0.28.5",
+    "css-loader": "^3.4.1",
     "enzyme": "^3.0.0",
     "enzyme-adapter-react-16": "^1.0.0",
     "eslint": "^4.4.1",
@@ -43,7 +45,8 @@
     "sassjs-loader": "^1.0.0",
     "style-loader": "^0.18.2",
     "url-loader": "^0.6.2",
-    "webpack": "^2.6.1"
+    "webpack": "^4.41.5",
+    "webpack-cli": "^3.3.10"
   },
   "jest": {
     "moduleDirectories": [