Fix package upgrade by moving all configuration in an INSTALL conditionnal

First sorry for the delay, free time is running low :(.

Also fix the pre/postupgrade to properly backup/restore site configuration.

I tested (only on DSM4) : 
 * new Install
 * Upgrade from 1.0.0RC1-1
 * Upgrade from 1.0.0RC2-2

And everything worked.

I also bumped the SPK_REV and altered the chown as @Diaoul requested.

It should fix #1220