This commit improves source code and tests.

Classes:
- LdapService: Refactor from LDAPConnector
- AccountController: Affected by LdapService refactor
- INotifiable: Remove deprecated "throws Exception" from interface
- JsonService: Implement JsonService
- NotificationService: Remove "async" string from logging
- WebSocketService: Replace getJsonList() into JsonService, add WS method wsPing(), remove unnecessary SuppressWarnings
- Notification: Add findByRenderedContent() to fetch notifications by rendered content
- FakeApplicationTest: Implement abstract class as "helper class" for tests, which requires a standard environment with HTTP context
- MockBaseModel, MockNotifiable: Implement mock for INotifiable interface for NotificationTest
- MockJsonSerializable: Implement mock for IJsonSerializable interface for JsonTest
- NotificationTest: Test for notifications
- WebSocketTest: Optimize WebSocketTest by using FakeApplicationTest, add testPing()
- IntegrationTest: Add JavaDoc, change method test() to not use lambda
- JsonTest: Test for JsonService
- TemplateTest: Test for TemplateService

JS:
- notifications.js. Remove deprecated params

Templates:
- template_test.scala.html: Add test template for TemplateTest
Merge remote-tracking branch 'origin/26_NotificationRefactoring' into 26_NotificationRefactoring
Merge branch '26_NotificationRefactoring' into develop