Introduce an option '--memory' for showing memory related
information. The memory bandwidth infomatio is listed as:

Domain: 'libvirt-vm'
 memory.bandwidth.monitor.count=4
 memory.bandwidth.monitor.0.name=vcpus_0-4
 memory.bandwidth.monitor.0.vcpus=0-4
 memory.bandwidth.monitor.0.node.count=2
 memory.bandwidth.monitor.0.node.0.id=0
 memory.bandwidth.monitor.0.node.0.bytes.total=10208067584
 memory.bandwidth.monitor.0.node.0.bytes.local=4807114752
 memory.bandwidth.monitor.0.node.1.id=1
 memory.bandwidth.monitor.0.node.1.bytes.total=8693735424
 memory.bandwidth.monitor.0.node.1.bytes.local=5850161152
 memory.bandwidth.monitor.1.name=vcpus_7
 memory.bandwidth.monitor.1.vcpus=7
 memory.bandwidth.monitor.1.node.count=2
 memory.bandwidth.monitor.1.node.0.id=0
 memory.bandwidth.monitor.1.node.0.bytes.total=853811200
 memory.bandwidth.monitor.1.node.0.bytes.local=290701312
 memory.bandwidth.monitor.1.node.1.id=1
 memory.bandwidth.monitor.1.node.1.bytes.total=406044672
 memory.bandwidth.monitor.1.node.1.bytes.local=229425152
Signed-off-by: NWang Huaqiang <huaqiang.wang@intel.com>