Add the ability to configure which Unix user that interacts with Choria governors

[JoshuaSmeda]

Puppet runs its process under root, and in our circumstance, we run our Choria governors under another non-privileged Unix user.

Please add the ability to configure which user the governor API interacts with as per the following, https://www.rubydoc.info/gems/puppet/Puppet%2FUtil%2FExecution.execute

:cwd => '/etc/choria', 
:uid => 1000

In this example, our specific Unix user id was 1000.

  def run(action, ens, args={})
    args.delete(:ensure)
    parse_result(Puppet::Util::Execution.execute(make_cmd(action, args), :cwd => '/etc/choria', :uid => 1000, :failonfail => true, :custom_environment => environment), ens)
  end

There are a number of other references in choria_governor.rb that would also need to be modified to handle non-UID 0 processes.

Please let me know if I can be of any help.