Fix unlimited stackable pool autobinding, fix unlimited pool quantity

Support quantities > 1 from unlimited multi-entitlement/stackable pools.

Fixed CoverageCalculator.getQuantityToCoverStack to work with unlimited pools, use it to get an upper bound for the quantity required of unlimited pools.

Use currently_available pool variable rather than modifying pool.quantity and pool.consumed.  This variable is created in the creation of autobind context (only available/used in autobind).

Removed date checking in autobind, the exact same check is done in pre-entitlement, and it was a pain to support in tests.