Just Pushed: More Dynamic Template work (breaking change)

Hi,

Two updates on dynamic mappings. The first is that the format has change,
and dynamic templates are now named. This allows for much simpler handling
when merging mappings. The second is that dynamic templates can only be
defined on the root level (object mapping) and apply to all inner object /
field. This provides much better behavior when introducing a new template to
a live system.

-shay.banon