Support or don't support strings

[jaxxstorm]

Currently, you can't specify a string for a fact value, like so:

::facter_tags::value { 'puppet':
    values => 'infra',
  }

The workaround is to always make values an array or a hash, but it would be nice to be able to specify a single tag and have it evaluated accordingly.

We should always return valid JSON, even if it's just a string based. An alternative is to disallow strings as a valid type for values

[jaxxstorm]

So the problem here is twofold,

We can't just have a single string in JSON, it's not valid 😢

There's a nice function in stdlib, but it's only Puppet 4 compatible 😢

https://github.com/puppetlabs/puppetlabs-stdlib#is_a

[jaxxstorm]

Additional note, can't use validate_hash or validate_array because it could be an array or a hash.