Use boolean for refreshonly

Puppet::Type supports `:boolean => true` to create a
`resource.<property>?` method that is true or false based on the
`:true`, `:false`, `true`, or `false` value of the parameter.

This will allow accurate assesment of the refreshonly attribute for
testing.
Add specs for psql Type and Provider
Merge pull request #212 from hunner/handle_refreshonly

Handle refreshonly correctly