olsrd: backward compatibility (config and init script)

This patch will introduce a backward compatibility with the previous init and config scripts.

 /etc/{config,init.d}/olsrd4 are renamed to /etc/{config,init.d}/olsrd
 
## IpVersion 6and4 
IpVersion 6and4 is deprecated, you should use /etc/config/olsrd6 for IPv6.

* In case of IpVersion 6and4 olsrd will behave as before but will warn you that the configuration is deprecated and you should use /etc/config/olsrd6 for IPv6.
* only /etc/init.d/**olsrd6** will refuse to start with IpVersion 6and4
* In 6and4 the hotplug script will not work (just as before) but it will works with if you use /etc/config/olsrd for Ipv4 only and /etc/config/olsrd6 for IPv6 

/cc: @zioproto