pload: make it a test service and not a public one

pload: make it a test service and not a public one

pload is a performance benchmark that measures the onwire
speed of corosync.

problem is that once pload has been executed, the cluster
is basically dead.

turn pload into a test tool, by removing corosync-pload tool
and user library.

cleanup pload code to make it more readable and drop lots
of unnecessary stuff.

add test/ploadstart tool that can configure and start pload
via cmap calls.

Signed-off-by: Fabio M. Di Nitto <fdinitto@redhat.com>
Reviewed-by: Steven Dake <sdake@redhat.com>