feat: change the home convention to xvdb1.ext4

Modify the naming convention for the virtual /hoe partition, from
xvda2.ext4 to xvdb1.ext4
feat: change the waiting mode for xen-login

In HVM mode, the remote console goes throught a virtual serial port
which is very slow, so move the loop delay of xen-login into the
command piped to 'xl console' to allow the last to receive and
transmit the answer.
feat: change the waiting mode for xen-command

In HVM mode, the remote console goes throught a virtual serial port
which is very slow, so move the loop delay of xen-command into the
empty command piped to 'xl console' to allow the last to receive and
transmit the answer.
feat: add the xen-hvm script to transform a PV domU into HVM domU

Add the xen-hvm scripts which takes an existing PV domU, as created by
xen-create and appy changes to transform it into an HVM domU.
The domU need to be booted to be transformed, so it must be valid and
functionnal.
All memory, vcpus and pinning settings are reset during the operation.
fix: add the HVM handling for xen-clone

Add a specific behavior for xen-clone to handle HVM domU cloning.
Merge branch 'xen-hvm' into develop
Merge branch 'develop'