Add an extra header/body separator CRLF to ensure the first line of the body does not become part of the header

[massar]

A very simple fix that likely went unnoticed for a while ;) Thanks for building this system @ytti and @job very cool and useful!

Add an extra header/body separator CRLF to ensure the first line of the body does not become part of the header

Funny that in both instances (set/clear) there was a single word before the ':', thus really making it look like a header ;)

Before for clearing the alarm:

List-Id: ring-sqa <sqa.ring.nlnog.net>
X-Mailer: ring-sqa
massar01.ring.nlnog.net: clearing ipv4 alarm
<Other headers added by spam systems etc>

<empty body>

Or for raising the alarm:

List-Id: ring-sqa <sqa.ring.nlnog.net>
X-Mailer: ring-sqa
Regarding: massar01.ring.nlnog.net ipv4
<anti-spam headers added by other systems>

This is an automated alert from the distributed partial outage
...

After this change:

List-Id: ring-sqa <sqa.ring.nlnog.net>
X-Mailer: ring-sqa
<anti-spam headers>

massar01.ring.nlnog.net: clearing ipv4 alarm

or for raising the alarm:

List-Id: ring-sqa <sqa.ring.nlnog.net>
X-Mailer: ring-sqa
<anti-spam headers added by other systems>

Regarding: massar01.ring.nlnog.net ipv4
This is an automated alert from the distributed partial outage
...

[ytti]

The bug isn't exactly "we forgot to add an empty line", the bug is that I added the empty line incorrectly.

I'm doing [header, ""].join("\n") + body, yielding result of header\n""body, while I needed to dy [header, "", body].join("\n"), or specifically [mail, "", @body].flatten.join("\n")

Now we keep the useless empty string at the end of the header array.

[ytti]

I've created another pull request, which attempts to solve the same, without leaving the useless empty string in front of the body.
As well as ensuring we don't have field separator in multiple places, in case we actually want CRLF instead of just LF, we'd only change one place.