This commit realises single email notifications for users, who wants to receive all notifications immediately. The sending of emails is realized using typesafehub mailer (https://github.com/typesafehub/play-plugins/tree/master/mailer). Also the show all notifications page is improved. Changes from master are also merged.

Classes:
- AccountController.java: Merge changes from master
- FriendshipController.java: Put notification type into createNotification()
- GroupController.java: Code improvements, put notification types into createNotification()
- Navigation.java: Add navigation level for notifications
- NotificationController.java: Remove deprecated methods viewAjax(), viewHistoryAjax(), and deleteAll(), add counting of all available notifications to showAll() for pagination
- PostController.java: Remove deprecated comment, put notification types into createNotification()
- ProfileController.java: Remove unnecessary constant PAGE, add controllers prefix to redirects etc. add handling of emailNotifications to update() of profile
- Secured.java: Merge changes from master, add code simplifications
- EmailNotifications.java: Add enumerations for currently possible states of emailNotifications in Account
- Account.java: Add attribute emailNotification to determine, if the user wishes to receive no, all or daily one email notification if new notifications appear
- EmailHandler: Add handler to send email, especially for email notifications
- Login.java: Merge changes from master
- NewNotification.java: Add JavaDoc and attribute isSent to determine, if a notification is already sent via email, implement method countNotificationsForAccountId() to cound all available notifications for a user (required for pagination in NotificationController::showAll())
- Notification.java: Mark class as @Deprecated
- NotificationHandler.java: Implement another async Akka process to actually sent email notifications (implement handleMail())
- Studycourse.java: Change method getAll() to be in a transaction as problems might appear, if we have the same primary keys in different tables

Templates/CSS:
- Emails/notificationsHtml.scala.html and Emails/notificationsPlainText.scala.html: Templates for emails (HTML template should get a style improvement)
- Notification/view.scala.html: Improve show all notifications by add pagination and better HTML
- Profile/edit.scala.html: Add emailNotifications select box for the user to choose, whether to receive no, all or daily email notifications
- snippets, feedback.scala.html, mail.scala.html: Merges from master
- htwplus.css: Add styles for show all notifications

Other:
- conf/application.sample.conf: Merge changes from master, add SMTP mailer settings and htwplus.email.sender for email notifications
- messages: Add i18n for email notifications and show all
- conf/play.plugins: Add file for mailer plugin
- build.sbt: Include mailer plugin information
- LICENSE: Add MIT license from master change