Containers support

[mahendrapaipuri]

Currently, the extension works on bare-metals and support for containers is very minimal. We need to explore supporting per container metrics if the host /proc can be mounted in the container. In that case, we can get container's CPU usage and host's CPU usage and so, we can split the energy usage of container.

If host;s /proc is not available, we can only report system wide energy usage. In any case we need /sys/fs/powecap needs to be mounted in the container.