False values for left outer and right outer join

[tdutrion]

Zend\Sql\Select contains constant declaration for both left and right outer join as follow:

const JOIN_OUTER_RIGHT = 'outer right';
const JOIN_OUTER_LEFT  = 'outer left';

Unfortunately, as described in the wikipedia article for instance, values should be respectively left outer and right outer instead of outer left and outer right.

[weierophinney]

Closed with #27