Use highest SSL version supported by both sides

See merge request esr/irker!10

do not hardcode syslog devices

See merge request esr/irker!11

Drop sorted() from event_handler

Closes #11

See merge request esr/irker!18

Feature/irkerhook py3k support

See merge request esr/irker!19

Fix incorrect filename in Makefile rule

See merge request esr/irker!17

This breaks on python 3 with "TypeError: unorderable types:"

The sorting was originally added to irclib to fix
https://sourceforge.net/p/python-irclib/bugs/9/
( in https://github.com/jaraco/irc/commit/ad159cbbf1d00fe15876a61d0abf88e43f5112ca)
but as irkerd doesn't have event priorties, the issue doesn't
apply here anyway.

This closes #11.

Only close the connection if it still exists

See merge request !16

run daemon as the irker user (Close: #832758)

See merge request !15

Only HTTPError has a code attribute

See merge request !14

Make systemd unit use a dedicated user, and note this in the install documentation

See merge request !13

improve irkerd.service

See merge request !12

self.connection is set to None if there is a timeout.

this is an improvement upon the default .service file. it requires a
irker user to be created, something which is automatically handled by
the debian package, but should be handled by other distributions when
deploying the .service file.

there are obvious dangers in running irkerd as root: a compromise
would be catastrophic, and since it runs on public servers that are
traditionnally pretty hostile (IRC), it seems critical that rights of
the daemon be limited.

irkerd should not be launched as root.

admins might not remember whether the service is called "irkerd" or
"irker".

"irker daemon" doesn't really describe the service to someone who
doesn't already know what it is.

the .service file does not currently point to the relevant
documentation.

this patch addresses all of the above issues.

in my specific use case (Debian Jessie), multiple of the candidates
exist, which makes the whole thing *crash* because there are more than
one candidates.

regardless, we shouldn't have to guess where syslog can be: it's the
stdlib's job to do the right thing and find the right device here.

otherwise this should be configurable. so revert part of the previous
commits and restore sanity.

Closes issue #1

Fix irk for Python 3 and Unicode input

There were several issues:
- json.dumps does not have an encoding parameter in Python 3.
- Forcing the json.dumps encoding to ASCII prevents any non-ASCII
  character in the message. To avoid having non-ASCII characters in the
  *dump*, the only needed parameter is ensure_ascii=True which is the
  default.
- To coerce a str to bytes in Python 3, an encoding must be provided
  even when it only contains ASCII characters.
  The solution is to use the encode() method which is available in both
  versions.

See merge request !7

There were several issues:
- json.dumps does not have an encoding parameter in Python 3.
- Forcing the json.dumps encoding to ASCII prevents any non-ASCII
  character in the message. To avoid having non-ASCII characters in the
  *dump*, the only needed parameter is ensure_ascii=True which is the
  default.
- To coerce a str to bytes in Python 3, an encoding must be provided
  even when it only contains ASCII characters.
  The solution is to use the encode() method which is available in both
  versions.