add get primary key helper
add get primary key helper

get non-standard primary keys
get failing test to pass

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