Adds support for localized push notification in push payload (#4129)

* Adds support for localized push data keys

- passign alert-[lang|locale] or title-[lang|locale] will inject the
  proper locale on the push body based on the installation

* Better handling of the default cases

* Updates changelog

* nits

* nits

spec/PushWorker.spec.js

@@ -1,4 +1,5 @@
 var PushWorker = require('../src').PushWorker;
+var PushUtils = require('../src/Push/utils');
 var Config = require('../src/Config');
 
 describe('PushWorker', () => {
@@ -54,4 +55,105 @@ describe('PushWorker', () => {
       jfail(err);
     })
   });
+
+  describe('localized push', () => {
+    it('should return locales', () => {
+      const locales = PushUtils.getLocalesFromPush({
+        data: {
+          'alert-fr': 'french',
+          'alert': 'Yo!',
+          'alert-en-US': 'English',
+        }
+      });
+      expect(locales).toEqual(['fr', 'en-US']);
+    });
+
+    it('should return and empty array if no locale is set', () => {
+      const locales = PushUtils.getLocalesFromPush({
+        data: {
+          'alert': 'Yo!',
+        }
+      });
+      expect(locales).toEqual([]);
+    });
+
+    it('should deduplicate locales', () => {
+      const locales = PushUtils.getLocalesFromPush({
+        data: {
+          'alert': 'Yo!',
+          'alert-fr': 'french',
+          'title-fr': 'french'
+        }
+      });
+      expect(locales).toEqual(['fr']);
+    });
+
+    it('transforms body appropriately', () => {
+      const cleanBody = PushUtils.transformPushBodyForLocale({
+        data: {
+          alert: 'Yo!',
+          'alert-fr': 'frenchy!',
+          'alert-en': 'english',
+        }
+      }, 'fr');
+      expect(cleanBody).toEqual({
+        data: {
+          alert: 'frenchy!'
+        }
+      });
+    });
+
+    it('transforms body appropriately', () => {
+      const cleanBody = PushUtils.transformPushBodyForLocale({
+        data: {
+          alert: 'Yo!',
+          'alert-fr': 'frenchy!',
+          'alert-en': 'english',
+          'title-fr': 'french title'
+        }
+      }, 'fr');
+      expect(cleanBody).toEqual({
+        data: {
+          alert: 'frenchy!',
+          title: 'french title'
+        }
+      });
+    });
+
+    it('maps body on all provided locales', () => {
+      const bodies = PushUtils.bodiesPerLocales({
+        data: {
+          alert: 'Yo!',
+          'alert-fr': 'frenchy!',
+          'alert-en': 'english',
+          'title-fr': 'french title'
+        }
+      }, ['fr', 'en']);
+      expect(bodies).toEqual({
+        fr: {
+          data: {
+            alert: 'frenchy!',
+            title: 'french title'
+          }
+        },
+        en: {
+          data: {
+            alert: 'english',
+          }
+        },
+        default: {
+          data: {
+            alert: 'Yo!'
+          }
+        }
+      });
+    });
+
+    it('should properly handle default cases', () => {
+      expect(PushUtils.transformPushBodyForLocale({})).toEqual({});
+      expect(PushUtils.stripLocalesFromBody({})).toEqual({});
+      expect(PushUtils.bodiesPerLocales({where: {}})).toEqual({default: {where: {}}});
+      expect(PushUtils.groupByLocaleIdentifier([])).toEqual({default: []});
+    });
+  });
 });