Use libpod instead of requiring external podman binary

[mohit-marathe]

Is your feature request related to a problem? Please describe.
Unlike dockerengine.go, podmanengine.go does not uses API. It instead uses exec.Command which requires podman binary to perform any operation.

Describe the solution you'd like
Use libpod

Additional context
#599 (comment)

[Sanket-0510]

Hey as per my understanding we can use libpod's library for the following:

1. Inspecting image using pod.InspectImage(<image_name>.
2. libpod's Imagepull function to pull the image
3. there is a function name createContainer to create and run the container.

@mohit-marathe I would like to take this issue.