- orm: Removed a lot of logging that nobody really cares about,

- orm: Removed a lot of logging that nobody really cares about,
logging that remains will respond to live changes in the
log level.  No significant overhead is added.  [ticket:1719]
- engine: Opened up logging a bit such that isEnabledFor() is called
more often, so that changes to the log level for engine/pool
will be reflected on next connect.   This adds a small
amount of method call overhead.  It's negligible and will make
life a lot easier for all those situations when logging
just happens to be configured after create_engine() is called.
[ticket:1719]