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

* add base class

* properties are static

* some fixes

* tslint

src/@ionic-native/core/ionic-native-plugin.ts

@@ -0,0 +1,41 @@
+export class IonicNativePlugin {
+
+  static pluginName: string;
+
+  static pluginRef: string;
+
+  static plugin: string;
+
+  static repo: string;
+
+  static platforms: string[];
+
+  static install: string;
+
+  /**
+   * Returns a boolean that indicates whether the plugin is installed
+   * @return {boolean}
+   */
+  static installed(): boolean { return false; }
+
+  /**
+   * Returns the original plugin object
+   */
+  static getPlugin(): any {}
+
+  /**
+   * Returns the plugin's name
+   */
+  static getPluginName(): string { return; }
+
+  /**
+   * Returns the plugin's reference
+   */
+  static getPluginRef(): string { return; }
+
+  /**
+   * Returns the plugin's install name
+   */
+  static getPluginInstallName(): string { return; }
+
+}