Save the user_id of the EndUser posting the message
Add base32 encode/decode implementation
Add ability to tag email reference ids

With the introduction of collaborators, this is necessary so we can determine who is replying without relying on the
FROM address - which can be easily spoofed.
Lookup thread based on tagged email reference IDs

Using email headers try to determine the user.
Refactor notification mechanism to collaborators

Make sure new message notice goes to the user who posted the message not
neccessarily the ticket owner.
Set the user ID of the user posting the message