Fix stat names so delete of stats on restart works

Folsom can get inconsistent. When it does stat updates will fail.
When a stat update fails the stat server crashes. Deleting on
start up is a way to get folsom consistent again.

This commit fixes a bug where the pipe stats were not all
deleted due to using the wrong stat name format.
Merge pull request #70 from basho/kv508-crashed-stats

Fix stat names so delete of stats on restart works
Roll riak_pipe version 1.3.1
Merge branch '1.3'

Conflicts:
	rebar.config