Removed redundant input. Update for get ajax.

Enabled ajax requests by get method, by changing `_POST` to `_REQUEST`.
Removed the old js functions and form inputs. Saved the countries for
the time being.
Fixed reset and insert/cancel embeds

The output will be of `[schema]` and `[scprop]` shortcodes. The latter
can not be automatically parsed because they can contain `[scmbed]`
which are embedded schemas with properties. Need to write the display
functions later.
Ajax by get. Enabled embeds.