Remove files from chrony.d to avoid unmanaged configuration options.

Signed-off-by: Georg Pfuetzenreuter <georg.pfuetzenreuter@suse.com>

Pool and server configuration may have different options but it's not
currently possible.
In order to solve that, the template is changed to accept pool
or server specification as a dictionnary, specifying at least the
pool/server name and if wanted the pool/server options. If no options
are specified, it'll use chrony.options.
In order to not break anything the template is checking if the server/pool
specification is a dictionnary or not, and acts accordingly.

Fixes: #27
Signed-off-by: Arnaud Patard <apatard@hupstream.com>