Implement the available pool as a LIFO instead of a FIFO. This allows connections to reach their maximum idle time so that they can be removed from the pool, unless we really do need to use that many simultaneous connections.
Merge pull request #34 from rankinc/xapool-lifo

Implement XAPool.availablePool as LIFO instead of FIFO.  Reviewed.
Allow setting a separate timeout for the JDBC4 connection test, which can be shorter than the acquisition timeout. This allows us to test several (say) Oracle server nodes behind a single SCAN hostname, should one node fail.
Merge branch 'connection-test-timeout' of https://github.com/rankinc/btm into connection-test-timeout