[RFE] Add flag to execute "Play ansible roles"

[giovannisciortino]

Satellite from version 6.4 support the execution on ansible roles associated to hosts.
A new flag on bootstrap.py script could be useful to trigger automatically the execution of the Ansible roles associated to the host after its registration.

Note: The ansible roles can be associated to an host during registration process associating them to a hostgroup.

This is an example of the API call used to trigger the execution of ansible roles :

[root@client ~]# curl -H "Accept:application/json,version=2" -H "Content-Type:application/json" -X POST -u user:password -k -d "{"job_invocation" : {"job_template_id": 126, "inputs": {}, "ssh": {}, "recurrence": {}, "scheduling": {}, "concurrency_control": {}, "search_query": "name = $(hostname)", "targeting_type": "static_query"}}" https://satellite.work.lab/api/job_invocations