Allow changing the configuration directory and files owner

[thias]

This is because it's good practice to keep the service from potentially overwriting its own configuration through some security flaw, meaning having the owner 'root', the group 'consul' and files mode 0640 and directories mode 0750 makes the most sense to keep everyting secure and private.

Note that this works for me because I deploy consul using an rpm where I have set the config directory to have mode 0750, but this is not something this Puppet module will be enforcing. Should a new config_dir_mode also be added, defaulting to undef to keep backwards compatibility?

[thias]

I've fixed the default value to now honor the "user" override, and also added a spec test to check for config dir and file ownership when this parameter is used.

[thias]

FYI, the failing check is because some CentOS 6 packages couldn't be installed for one of the jobs.

[thias]

@solarkennedy : Any feedback on this change? It's fairly straightforward, passes checks and (to me at least) makes a lot of sense security-wise.

[solarkennedy]

I think this is fine