kes Simplify locking in the reservations system.

kes  Add more debug code in reservations.
kes  Make sure error condition on reserving a volume is handled correctly.
kes  Correct handling of volume_in_use.
kes  Correct handling of initializing a device.
kes  Move handling of broadcasting releasing a device into release_device().
kes  Correct attaching dcr to dev so that it is only done if device
     is properly initiated.