Merge pull request #1 from web2py/master

Syncing with upstream.
Modified DAL and DB2 adapter to allow use of the official ibm_db_dbi driver or ODBC.
Allow URI for ibm_db_dbi driver to user lower or upper case params.
Merge pull request #537 from btreecat/master

Add option of using offical ibm_db_dbi driver instead of ODBC driver for DB2