core, engine, webadmin: Consider only online logical CPUs

This patch reports the ids of the logical CPUs which are online in the
Hosts tab of the webadmin interface, and uses this information to
validate the CPU pinning during the VM creation.

A new column in the vds_dynamic table was added to store this list.

Change-Id: Ib20f20d6003502fe2f2864abb5ad8f4f5a19ecdc
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1148092
Signed-off-by: Vitor de Lima <vdelima@redhat.com>