improve OracleExceptionSorter
add testcase
OracleExpceptionSorter add fatal error code 17442
improve dynamic config support for DruidDataSourceStatLogger
0.2.21
improve dynamic config support for ValidConnectionChecker
Merge remote-tracking branch 'origin/master'
fixed testcase
validConnectionChecker support dynamic config
improve wallfilter
Merge remote-tracking branch 'origin/master'
Merge pull request #348 from wenshao/master

request for bulk integrate