avahi: trim descriptions of HTTP and SSH services

This makes the description of the HTTP and SSH services look the
same as in other distributions as suggested by kirelagin in #543.

Signed-off-by: Michael Heimpold <mhei@heimpold.de>
avahi: factor out service files into own packages

This allows the user to select individual services to be announced
via Avahi.

Signed-off-by: Michael Heimpold <mhei@heimpold.de>
openssh: provide an avahi service file

As discussed in #543, we can announce the SFTP service via Avahi
when sftp-server is installed.

Signed-off-by: Michael Heimpold <mhei@heimpold.de>
mpd: factor out avahi service file

As discussed in #543 provide the avahi service file within its own
tiny package to allow the user to choose which services are
announced.

Signed-off-by: Michael Heimpold <mhei@heimpold.de>

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The former avahi service file was only installed for mpd-full. Does
the mpd-mini does not support network functionality?

Then we should adjust deps here...
Merge pull request #618 from mhei/avahi

Avahi service file packages