feat(plugin): add device motion plugin

src/plugins/devicemotion.ts

@@ -0,0 +1,26 @@
+import {Plugin, Cordova} from './plugin';
+
+/**
+ * Requires Cordova plugin: `cordova-plugin-device-motion`. For more info, please see the [Device Motion docs](https://github.com/apache/cordova-plugin-device-motion).
+ *
+ * ```
+ * cordova plugin add https://github.com/apache/cordova-plugin-device-motion.git
+ * ````
+ *
+ * @usage
+ * ```js
+ * ```
+ */
+@Plugin({
+  plugin: 'https://github.com/apache/cordova-plugin-device-motion.git',
+  pluginRef: 'navigator.accelerometer'
+})
+export class DeviceMotion {
+
+    // This Promise is replaced by one from the @Cordova decorator that wraps
+    // the plugin's callbacks. We provide a dummy one here so TypeScript
+    // knows that the correct return type is Promise, because there's no way
+    // for it to know the return type from a decorator.
+    // See https://github.com/Microsoft/TypeScript/issues/4881
+
+}