checkimages vdsm hook
=====================
Hook performs consistency check on all qcow2 format disk images of a
particular VM using the QEMU disk image utility.

Accepts optional parameter 'timeout' (in seconds) to specify how long
the hook should wait for the QEMU disk image utility operation to complete.

Without 'timeout' specified, particular timeout is computed based on
image size.

syntax:
    checkimages=true(|,timeout:\d+\.{1}\d+);

example:
    checkimages=true,timeout:1.12     # Use 1.12 seconds as timeout

    checkimages=true                  # Compute timeout based on image size

Note: Timeout value is taken in seconds. Check of 1GB image takes ~0.02 s.

