Add parameter outofsync_interval

[WoutResseler]

Add the parameter outofsync_interval to make it configurable from puppet and over writable from possible hiera config

[ekohl]

This is IMHO a duplicate of #1007. It's true you can't set it via Hiera and it's using the CLI so it won't end up as a read-only setting, but I'd prefer to avoid adding all settings as parameters on init.pp. Perhaps we can add it to foreman::settings so you can set it via Hiera? That could use foreman::settings_fragment.