Add PING_TYPE_INSERT

To detect a failure like mysqld can accept a new connection and can respond
a simple select queries, but cannot respond insert/update/delete queries.

In particular, I want to detect hardware trouble (disk failure or RAID
controller failure) and perform fail over automatically.
Reformat source code by perltidy -i=2
Merge pull request #41 from hirose31/feature/ping-insert

Add PING_TYPE_INSERT