Improves Controller and Adapter relationship

- Controllers that have adapters are AdaptableControllers
- AdaptableController is responsible to instantiate the proper adapter if needed (string, function or BaseAdapter)
- BaseAdapter is the base class for adapters, allows skipping when passed directly to the controller

src/Adapters/Push/PushAdapter.js

@@ -8,10 +8,47 @@
 //
 // Default is ParsePushAdapter, which uses GCM for
 // android push and APNS for ios push.
+
 export class PushAdapter {
   send(devices, installations) { }
 
-  getValidPushTypes() { }
+  /**
+   * Get an array of valid push types.
+   * @returns {Array} An array of valid push types
+   */
+  getValidPushTypes() {
+    return this.validPushTypes;
+  }
+  
+  /**g
+   * Classify the device token of installations based on its device type.
+   * @param {Object} installations An array of installations
+   * @param {Array} validPushTypes An array of valid push types(string)
+   * @returns {Object} A map whose key is device type and value is an array of device
+   */
+  static classifyInstallation(installations, validPushTypes) {
+    // Init deviceTokenMap, create a empty array for each valid pushType
+    let deviceMap = {};
+    for (let validPushType of validPushTypes) {
+      deviceMap[validPushType] = [];
+    }
+    for (let installation of installations) {
+      // No deviceToken, ignore
+      if (!installation.deviceToken) {
+        continue;
+      }
+      let pushType = installation.deviceType;
+      if (deviceMap[pushType]) {
+        deviceMap[pushType].push({
+          deviceToken: installation.deviceToken,
+          appIdentifier: installation.appIdentifier
+        });
+      } else {
+        console.log('Unknown push type from installation %j', installation);
+      }
+    }
+    return deviceMap;
+  }
 }
 
 export default PushAdapter;