Allow for meridian_server to be restarted

[wfvining]

Add a version number (or perhaps a "ref" from erlang:make_ref/0) to the node name in the vector clock. A new ref or version number is created every time the server is restarted, in this way there will be no consistency issues caused by the server's clock restarting from zero --- every time the server is restarted it is considered a new server in the vector clocks of all other servers. NOTE: PIDs cannot be used reliably as a version number as they may be reused in a long running system (I think, although the documentation on this is unclear). Refs won't repeat for 500+ years when created at a rate of 1 per ns, so they should be just fine as version numbers.