Add rule to enforce string quoting style

[nre-ableton]

Although Ansible's YAML documentation does not make specific recommendations on quoting style, it implicitly prefers unquoted strings except for the numerous YAML "gotchas". However, an info box in the Windows usage documentation says:

You should only quote strings when it is absolutely necessary or required by YAML, and then use single quotes.

IMHO this isn't a very good best-practice for playbooks, but I wish that whatever the preferred quoting style is, ansible-lint had some built-in capabilities to enforce it.

[nre-ableton]

(Somewhat related to #584)

[bbaassssiiee]

For more views: https://stackoverflow.com/questions/19109912/yaml-do-i-need-quotes-for-strings-in-yaml