directories are either a Hash or an Array of Hashes

this should fix #535

n.b.: older versions of puppet do not support unless
btw: When you switch from unless to if, you must also switch from
'foo or bar' to '!foo and !bar', because, logic.
Merge pull request #536 from igalic/validate_directory

make sure that directories are actually a Hash
Merge branch 'master' of github.com:3flex/puppetlabs-apache