fix: move default plugin to package.json (#56)

Current versions of Cordova expect dependencies to be defined in
package.json. This updates the sample app to adhere to that practice.

Fixes #39
diff --git a/template_src/config.xml b/template_src/config.xml
index ad14b62..997ac90 100644
--- a/template_src/config.xml
+++ b/template_src/config.xml
@@ -27,7 +27,6 @@
     </author>
     <content src="index.html" />
     <!-- Whitelist configuration. Refer to https://cordova.apache.org/docs/en/edge/guide_appdev_whitelist_index.md.html -->
-    <plugin name="cordova-plugin-whitelist" spec="1" />
     <access origin="*" />
     <allow-intent href="http://*/*" />
     <allow-intent href="https://*/*" />
diff --git a/template_src/package.json b/template_src/package.json
index 2938f5a..d1ab3e0 100644
--- a/template_src/package.json
+++ b/template_src/package.json
@@ -11,5 +11,13 @@
     "ecosystem:cordova"
   ],
   "author": "Apache Cordova Team",
-  "license": "Apache-2.0"
+  "license": "Apache-2.0",
+  "devDependencies": {
+    "cordova-plugin-whitelist": "^1.3.4"
+  },
+  "cordova": {
+    "plugins": {
+      "cordova-plugin-whitelist": {}
+    }
+  }
 }