fix vmparking_delete

deletion needs a callback
use closure for unpark instead of functools.partial
fix vmparking's updatexml command

also fixes a bug with vms started elsewhere due to bad indentation
new tests for vmparking's updatexml
fix behaviour when sending faulty updatexml queries
add expliciting booting msg in status

"Online (Initializing VMs...)"
then
"Online(1)"
add a fallback to start vms when central agent is not detected
change timeout value to 20 ticks

to accomodate case when central agent and hypervisor start at the same
time
fix issue with delete vms started elsewhere

problem with sqlite query resulting in invalid removal of vms.
new tests for archipel-agent restart

when vms are instanciated, with/without central agent