Specify email sender and subject when sending confirmation email

[jace]

If a user makes a new account manually in Lastuser and then proceeds to post a job on Hasjob, they get a confirmation email each from Lastuser and Hasjob. If the latter goes to spam or bounces (see #226), there is no indication to the user that they were supposed to receive two confirmation emails.

While there is a larger requirement to reduce these dupe email verifications, Hasjob could make a quick fix by letting the user know the sender and subject of the email sent, perhaps with a preview:

From: Hasjob <no-reply@hasgeek.com>
To: User <user@example.com>
Subject: Confirmation of your job post

Preview here