qemu: Add the capabilitie to detect if the qemu binary have the capability to use bps_max and friends

Add a value in the enum virQEMUCapsFlags for the qemu capability.
Set it with virQEMUCapsSet if the binary suport bps_max and they friends.

Signed-off-by: Matthias Gatto <matthias.gatto@outscale.com>
qemu: Add bps_max and friends qemu driver

Add suport for bps_max and friends in the driver part.
In the part checking if a qemu is running, check if the running binary suport bps_max,
if not prrint an error message, if yes add it to "info" variable

Signed-off-by: Matthias Gatto <matthias.gatto@outscale.com>
qemu: Add bps_max and friend to domain_conf

Allow qemu driver to save the configuration use by bps_max and they friends.

Signed-off-by: Matthias Gatto <matthias.gatto@outscale.com>
qemu: Add bps_max and friends QMP suport

Detect if the the qemu binary currently in use suport the bps_max option,
If yes add it to the command, if not, just ignore the options.

Signed-off-by: Matthias Gatto <matthias.gatto@outscale.com>
qemu: Add bps_max and friends "text" suport

Detect if the the qemu binary currentely in use suport the bps_max option and thy firends,
If yes add it to the commande, if not, just ignore the options.

Signed-off-by: Matthias Gatto <matthias.gatto@outscale.com>
qemu: add bps_max and friends to qemu command genaration

Check the avability of the options with the current qemu binary, add them in the varable opt if yes,
print a message if not.

Signed-off-by: Matthias Gatto <matthias.gatto@outscale.com>
qemu: Add bps_max and friends to virsh

Add the new throttle options to virsh, and send them to libvirt.

Signed-off-by: Matthias Gatto <matthias.gatto@outscale.com>