crond service not optional
httpd service not optional
Unify http start/stop functions
Create function to start/stop all optional services
Add daapd to optional services functions
Simplify and extend usage of dlna_start/stop_daemon functions
Move daapd related functions from dlna to services
Allow explicit service list for start/stop all services
Drop check for Enable within services start functions
Remove all explicit start/stop functions for optional services
Add functions to start stop DNSR
Simplify process killing on stop functions
Start and stop DNSR along daapd
Decouple DNSR and daapd configuration change functions
Decouple daapd start and modify_config functions
Join daapd and DNSR configuration changes
Remove some unrequired configuration changes
Simplify function to set system time
Remove duplicated udhcpc script overlayed by /usr mount
Add clusters for services start/stop functions