[Pgbuildfarm-members] mail notification option

I am considering adding an option to allow you to specify a list of
addresses to notify of buildfarm events for your members via email. Mail
notifications have long been requested, so this is a small first cut.

Basically, it would work thus:

in your config file, put a setting like this:

mail_events => { all=> ['me(at)foo(dot)bar(dot)com', 'him(at)baz(dot)blurfl(dot)com'}],
failures => 'bzzt(at)my(dot)alarm(dot)com' },

The allowed event keys in this hash would be:
all: every build status received
failures: every non-OK build status received
all_changes: every time status changes
green_changes: every time status changes to/from OK

The corresponding values in the hash can be an arrayref of email
addresses, or a single scalar email address.

The notification sent by the server would look something like this:

----------------
Subject: PGBuildfarm member <membername> Branch <branchname> Status
[changed to] <status>

The PGBbuildfarm member <membername> had the following event on branch
<branch>:

Status: <status> (or Status Change from <oldstatus> to <newstatus>)

The snapshot timestamp for the build that triggered this notification
is: <YYYY-MM-DD HH::mm::ss>

The specs of this machine are:
OS: <osname> <osversion>
Arch: <architecture>
Comp: <compiler> <compiler-version>

For more information, see
http://www.pgbuildfarm.org/cgi-bin/show_history.pl?nm=<name>&br=<branch>

----------------------

In addition, I am thinking of setting up mailing lists that digest all
these event sets for all members over a 24 hour period, and that anyone
can subscribe to.

thoughts?

cheers

andrew