Add support to specifying hostname for create_container
Add support to specifying hostname for create_container

- This allows that nodes can specify the hostname of choice
- In the openswitch node, the default hostname is 'switch'
- Clarify that tag must be specified in image param

Signed-off-by: Walinton Cambronero <1f04f885082cc0892df9219a8132f4f8086a7db5@hpe.com>

fonsecamau/topology_docker_openswitch,HPENetworking/topology_docker_openswitch