added optional hiera merge functionality
Add spec tests for hiera_merge

Test for hiera_merge set to an invalid type that is not checked in the
code's case statement. Also test for error message returned from
validate_re().
Merge pull request #48 from ghoneycutt/hiera_merge

Hiera merge
Release v3.6.0 - Add ability to do merge lookup for ssh keys

Add parameter, hiera_merge, which lets you do a merge lookup through the
use of hiera_hash() for ssh keys.
Added Solaris OS support #22