Adding --log_cadvisor_usage flag to log the resource usage of cAdvisor.

This helps during performance analysis.
Merge pull request #269 from vmarmol/self-monitor

Adding --log_cadvisor_usage flag to log the resource usage of cAdvisor.
LXC Factory and Handler

This factory and handler can retrieve memory, cpu, diskio, and network information of lxc containers.
The handler can be passed additional container information(e.g. network interface) using a cdesc.json file
NetworkInterface now contains both VethHost and VethChild
Updated import and comments
Added network stats to raw handler

Raw handler now parses an optional json file with the network interface information, and emits network stats.
Fixed formatting
Renamed container description types
matches with the full path of the container