Fix key generation

[emning]

This fixes eyaml key generation on Puppet open source, which would error out with messages like:

Error: Could not find command '/usr/bin/puppet/eyaml'

As the eyaml binary may be in one of several directories depending on both OS and which gem provider is in use, switch to using a search path, and make it configurable.

This should cover both #30 and #32, and also work on Ubuntu versions where gems end up in /usr/local/bin.

[igalic]

+1

[shoekstra]

This fixed it for me on Ubuntu.

One thing though, specifying the $hiera::cmdpath wouldn't do anything because $hiera::eyaml::cmdpath is being getting the value of $hiera::params::cmdpath.

Please could you update your PR to rectify this (either removing the inheritance as in my commit or by inheriting from the hiera class instead of hiera::params).

Cheers,
Stephen