Refactor the "harakiri" command stuff

Harakiri means performing suicide (ritual), so the names
HarakiriCommand / HarakiriDispatcher etc seemed a bit off.

This patch moves the non-harakiri stuff over to the control
package and names them MockCommand/MockDispatcher etc.

The individual command handlers are pushed into a handlers
package.

Change-Id: I9f94a317dde4b5415a8531783b246fc8ac9776af
Reviewed-on: http://review.couchbase.org/27804
Tested-by: Trond Norbye <trond.norbye@gmail.com>
Reviewed-by: Mark Nunberg <mnunberg@haskalah.org>