DNN-4847

Necessary changes for supporting action links in notification e-mails. The changes affect towo notfications:

- Friend request
- follow back request

for both cases a couple of static resources and changes to the messaging scheduler have been added.
The message class itself has a new property NotificationTypeId which was available in the database already, just not in the code yet. 

This will basically add two links to a notification e-mail about a new friend /follow back request:

1. accept
2 view profile

both links point to the User profile page as set in portalsettings. The ViewProfile module then further processes the actions.

Another change to the global resource file adds a link to the message center page and a link to the user's profile sending the request.