feat(): add IonicNativePlugin base class (#1425)

* add base class

* properties are static

* some fixes

* tslint

src/@ionic-native/plugins/pedometer/index.ts

@@ -1,4 +1,4 @@
-import { Plugin, Cordova } from '@ionic-native/core';
+import { Plugin, Cordova, IonicNativePlugin } from '@ionic-native/core';
 import { Observable } from 'rxjs/Observable';
 import { Injectable } from '@angular/core';
 
@@ -22,7 +22,7 @@ export interface IPedometerData {
  *
  * @usage
  * ```
- * import { Pedometer } from 'ionic-native';
+ * import { Pedometer } from '@ionic-native/pedometer';
  *
  * Pedometer.isDistanceAvailable()
  *   .then((available: boolean) => console.log(available))
@@ -42,7 +42,7 @@ export interface IPedometerData {
   platforms: ['Android', 'iOS']
 })
 @Injectable()
-export class Pedometer {
+export class Pedometer extends IonicNativePlugin {
 
   /**
    * Checks if step counting is available. Only works on iOS.