Merge pull request #9 from alfmel/bc0ffd0

Add use declarations
Merge pull request #11 from alfmel/4fd981f6d7

Improve PDO compatibility and other code clean-ups
Merge pull request #12 from alfmel/2ada9c72c9

Add support for more fetch modes.
added support for PDO::ATTR_ORACLE_NULLS attribute
Merge pull request #1 from yajra/master

Upstream fixes