Add NotificationRecipient in the admin site
Add NotificationRecipient in the admin site

This allows to quickly see notifications that where not sent for various
reasons.

Change-Id: Iaa17006e1c7bf4ab73ae143f676118a3a831e767

Linaro/lava-server,Linaro/lava-server,Linaro/lava-server,Linaro/lava-server