Feature #1691: Add support in core for nic attach/detach. Thanks to Simon Boulet for his help.

Next step is to add NIC_ID attribute to each NIC, and process ATTACHNIC in driver manager
Feature #1691: Add the attribute NIC_ID to each NIC
Feature #1691: Add attach/detach nic methods to CLI and Ruby OCA
Feature #1691: Process VMM driver attach/detach nic response
Feature #1691: Add attach/detach nic methods to Java OCA
Feature #1691: Add NIC_ID attribute in db migrator
Feature #1224: New method one.vm.snapshotcreate
Feature #1224: Fix snapshot attribute creation
Feature #1224: New command onevm snapshot-create
Feature #1739: Fix bug in VM monitoring parser
(cherry picked from commit 0277e7430a993b3c24e7496134566bf619f4142e)
Feature #1224: Add snapshot_create vmm/kvm driver action
Feature #1224: Add placeholder for vmware and xen snapshot_create actions
Feature #1224: Return proper hypervisor_id to the core
Feature #1224: Remove debugging info
Feature #1224: Add snapshot_revert driver action
Feature #1224: Fix snapshotting not supported message for VMware
Feature #1224: New xmlrpc method one.vm.snapshotrevert
Feature #1224: New command onevm snapshot-revert
Feature #1224: Fix bug in onevm snapshot-revert
Feature #1224: Accept empty names for new snapshots