feat(stepcounter): add stepcounter plugin (#607)

* feat(stepcounter): add stepcounter plugin

* docs(stepcounter): add missing returns

src/plugins/stepcounter.ts

@@ -0,0 +1,73 @@
+import { Plugin, Cordova } from './plugin';
+/**
+ * @name Stepcounter
+ * @description
+ * Cordova plugin for using device's stepcounter on Android (API > 19)
+ *
+ * Use to
+ * - start and stop stepcounter service
+ * - read device's stepcounter data
+ *
+ * @usage
+ * ```
+ * import { Stepcounter } from 'ionic-native';
+ *
+ * let startingOffset = 0;
+ * Stepcounter.start(startingOffset).then(onSuccess => console.log('stepcounter-start success', onSuccess), onFailure => console.log('stepcounter-start error', onFailure));
+ *
+ * Stepcounter.getHistory().then(historyObj => console.log('stepcounter-history success', historyObj), onFailure => console.log('stepcounter-history error', onFailure));
+ *
+ * ```
+ */
+@Plugin({
+  plugin: 'https://github.com/texh/cordova-plugin-stepcounter',
+  pluginRef: 'stepcounter',
+  repo: 'https://github.com/texh/cordova-plugin-stepcounter',
+  platforms: ['Android']
+})
+export class Stepcounter {
+
+  /**
+   * Start the step counter
+   *
+   * @param startingOffset {number} will be added to the total steps counted in this session
+   * @return {Promise} Returns a Promise that resolves on success or rejects on failure
+   */
+  @Cordova()
+  static start(startingOffset: number): Promise<number | any> { return; }
+
+  /**
+   * Stop the step counter
+   * @return {Promise} Returns a Promise that resolves on success with the amount of steps since the start command has been called, or rejects on failure
+   */
+  @Cordova()
+  static stop(): Promise<number | any> { return; }
+
+  /**
+   * Get the amount of steps for today (or -1 if it no data given)
+   * @return {Promise} Returns a Promise that resolves on success with the amount of steps today, or rejects on failure
+   */
+  @Cordova()
+  static getTodayStepCount(): Promise<number | any> { return; }
+
+  /**
+   * Get the amount of steps since the start command has been called
+   * @return {Promise} Returns a Promise that resolves on success with the amount of steps since the start command has been called, or rejects on failure
+   */
+  @Cordova()
+  static getStepCount(): Promise<number | any> { return; }
+
+  /**
+   * Returns true/false if Android device is running >API level 19 && has the step counter API available
+   * @return {Promise} Returns a Promise that resolves on success, or rejects on failure
+   */
+  @Cordova()
+  static deviceCanCountSteps(): Promise<boolean | any> { return; }
+
+  /**
+   * Get the step history (JavaScript object)
+   * @return {Promise} Returns a Promise that resolves on success, or rejects on failure
+   */
+  @Cordova()
+  static getHistory(): Promise<any> { return; }
+}