Notifications: checking teplate syntax when create

- the NotifTemplateMessage syntax is checked before storing in DB when
  creating or updating
Notifications: fix bug in constraints of receiver

- two receivers with the same target(email) templateId and locale are not
  allowed
- this commit adds the templateId
Notifications: log undefined values

- undefined values were skipped, but not logged - this commit adds
  logging
Notifications: limit for life time of poolmessages

- pool messages are deleted from db after certain time limit (now set to
  10 days)
Merge pull request #576 from jirmauritz/notification

Notifications: checking teplate syntax when create and set time limit for pool messages