fix: package.json & package-lock.json to reduce vulnerabilities (#591)

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JS-BOWER-73627
- https://snyk.io/vuln/SNYK-JS-NODEEXTEND-73641
- https://snyk.io/vuln/npm:https-proxy-agent:20180402

package.json

@@ -21,7 +21,7 @@
     "babel-plugin-transform-runtime": "^6.23.0",
     "babel-preset-env": "^1.6.1",
     "babel-preset-es3": "^1.0.1",
-    "bower": "^1.8.2",
+    "bower": "^1.8.8",
     "bower-resolve-webpack-plugin": "^1.0.5",
     "chalk": "^2.1.0",
     "chokidar": "^2.0.0",
@@ -44,7 +44,7 @@
     "is-ci": "^1.0.10",
     "json-loader": "^0.5.7",
     "karma": "^1.7.1",
-    "karma-browserstack-launcher": "^1.3.0",
+    "karma-browserstack-launcher": "^1.4.0",
     "karma-chrome-launcher": "^2.2.0",
     "karma-mocha": "^1.3.0",
     "karma-scss-preprocessor": "^3.0.0",
@@ -61,7 +61,7 @@
     "mockery": "^2.1.0",
     "mustache": "^2.3.0",
     "node-sass": "^4.9.2",
-    "node.extend": "^2.0.0",
+    "node.extend": "^2.0.1",
     "npmconf": "^2.1.2",
     "pa11y": "^5.0.2",
     "parse-gitignore": "^0.4.0",