improved sql parser for postgresql, support create table inherits
add PGExceptionSorter
Merge pull request #730 from wenshao/master

add PGExceptionSorter
fixed compile error in macos
pg sqlparser support drop table if not exists
Merge pull request #731 from wenshao/master

pg sqlparser support drop table if not exists
register driver mbean error log level
Merge pull request #732 from wenshao/master

register driver mbean error log level
change oracle valid connection impl
Merge pull request #733 from wenshao/master

change oracle valid connection impl