testconf: restructure rpc methods and add dynamic loading

Also implement 'rpc-error' statement, switch to using config module and
move more funcionality into netconf.

Signed-off-by: Petar Koretic <petar.koretic@sartura.hr>
netconf: add methods implementation

Signed-off-by: Petar Koretic <petar.koretic@sartura.hr>
server: methods: example syslog method

Signed-off-by: Petar Koretic <petar.koretic@sartura.hr>