Adapt Puppet to use Hiera for parameters instead of a class

This should resolve the problems with recent versions of Vagrant. It moves what was previously in the params class into the default parameters supplied to each of the Puppet classes for Joindin::Web, Joindin::Sql, etc. These can then be overridden by copying the supplied common.yaml.dist to common.yaml and editing the options to suit. The defaults should however create a working system for the common case.