Require smokeping installed before creating dirs

On Ubuntu, the smokeping user is created by the package, so this patch
adds a dependency that requires the package be installed before creating
directories that are owned by the user.
Allow arbitrary probe config values

This changes the statically configured options for binary and step to
allow configuring any probe configuration that is passed in the hash by
the user.  This is needed for probes like AnotherDNS that have no binary
option, but have other useful options.