Split bg mgr table into two tables.
* Info is a set (new).
* Token/Lock entries is a bag (unchanged).
* Update supervisor to start table manager with both tables, with correc properties.
* BG-MGR must now wait until both tables are claimed before servicing calls.
* Remove superfluous ETS delete on 'set' table.
* Update EQC and EUnit tests to use new tables.
* Fix discovered bug in EQC head/tail tests - don't reverse history until it's used.

Remove superfluous ETS delete on a set table.