Detect identity columns in db2 structure_dump
Detect identity columns in db2 structure_dump

Suggested fix for #203. Adds a test for JDBC getColumns field 23,
IS_AUTOINCREMENT. If 'YES', assume GENERATED ALWAYS AS IDENTITY for the
column (don't believe the JDBC adapter reports this with any more
granularity, see JDBC API docs: http://bit.ly/LxjW8f).

jruby/activerecord-jdbc-adapter,kares/activerecord-jdbc-adapter,bruceadams/activerecord-jdbc-adapter,bruceadams/activerecord-jdbc-adapter,jruby/activerecord-jdbc-adapter,jruby/activerecord-jdbc-adapter,keeguon/activerecord-jdbc-adapter,keeguon/activerecord-jdbc-adapter,kares/activerecord-jdbc-adapter,bruceadams/activerecord-jdbc-adapter,kares/activerecord-jdbc-adapter,keeguon/activerecord-jdbc-adapter