1.10: Remove array and string notation for dialog's position option

[jzaefferer]

Can't land this in master while that serves for 1.9 docs.

See also http://bugs.jqueryui.com/ticket/8824

[jzaefferer]

I'll leave this closed, opened #73 to keep track of 1.10 updates.

[scottgonzalez]

These shouldn't be removed. They need to be marked as deprecated.