use priority for intercom notifications

[hvorragend]

with mailer 2.0 you will have the possibility to add a priority to your email for the mail queue handling.

the sendmessage api function of the mailer module will accept a new parameter "priority" with value 1-10. 1=highest.
PN notifications should become a high priority to support fast user interaction.

maybe you can add "priority" with 2 for notifications. Otherwise default will be 5 for not adding a priority