Convert True/False values in strict_host_key_checking

[johnnoone]

This PR converts True/False values into yes/no for strict_host_key_checking, and fix the full yaml for playbooks.

For example

- ssh_config:
    user: vagrant
    host: example.com
    strict_host_key_checking: true

is equivalent to

- ssh_config: >
    user=vagrant
    host=example.com
    strict_host_key_checking=yes