New feature (fix for someone...): don't erase user's home if the computer crashes or reboots during the exam.
The user's home is erased (if required) only when the exam mode starts the first time.

Fix: if the web service does not reply on machine boot, try 5 times then switch to graphical target.
If the WS does not reply when the machine is already in some exam mode or normal, do nothing.

Runtime parameters change had to depend on esame-get-config-boot service instead.
FIX2: firefox home set at runtime now kill every firefox instance before update firefox config file.

Fixed get-config to work on machines that were turned off in exam mode and must wake up in normal mode.