Removed index; introduced id

but replaying from a certain id is missing. and the problem of event
order has to be solved with regard to timestamp resolution.
Revert "Removed index; introduced id"

This reverts commit ab0d20609f69b1ab547e2cd35e61fd6292aa909f.
Changed index:long to sequencenumber:string

That way each store can decide how to best encode the ordering of
events.
Storing timestamp as UTC

bug fix: sqlite sequence number in queries should be an int, not a
string
Introduced an id:Guid for events