In order to allow easier testing of the argument parser,
refactor its setup into a function. Now we can
"from xmppnotify import build_argparser" and use it.

Missed to remove some spaces in the last commit.
(I never saw notification comments on our system yes...)

Most xmpp clients display messages using a variable width
font. Aligning stuff using spaces doesn't work there.
On mobile clients spaces even add to the message's display
size without adding useful content.

So strip spaces!

{hostname} and {servicename} are the technical/config
names. Get them together on one line and call them "Ref:".
They're references to the config, really.

icinga2 has a "notification type". This is usually
"PROBLEM" or "RECOVERY".

Changed the first line of the message to be like the
Subject of the common notification mails. Especially having
the notification type at the beginning is great for reading
messages on the go ("RECOVERY? Don't even need to read the
remainder NOW").

Basicly removed the "*** monitoring" line. The only
relevant information in it was the monitoringhost.
I could argue that admins probably don't really need that
info at all (the affected host(displayname) should be more
unique, really), but nevertheless re-added the monitoring
host at the end in a smaller line for now.