Ensure that all hiera key/values are strings
Correct hierarchy
Leave hiera values alone, hiera itself will serialize/filter these
Correct syntax for base.pp
Add support for specifying classes/hiera config on platform level
Error handling for remote SSH commands.

Previously, Kitchen::SSH would assume all that all commands returning an
exit code >0 had failed. This assumption is not true for Puppet; the
agent may return 0 or 2, both of which indicate success. Therefore
there's now an additional method that provisioners may implement:
run_command_exit_codes, which should return an array specifying expected
exit codes (default is [0], i.e. the old behavior).
Style fixes