BACKLOG-674 - CLONE - REG: HDP21:Hive: if we change the db-scheme, then it
won't be used until pooling connection has closed; the original will be
used instead.

What was done:
1) changed key for building pool name so it takes host, port and db into consideration  now
Merge pull request #745 from kolinus/backlog-674

BACKLOG-674 - CLONE - REG: HDP21:Hive: if we change the db-scheme, then ...