Add dialyzer target and initial ignore file to riak_test

This PR adds a dialyzer target to riak_test.

Makefile has new targets, but the public entry is "make dialyzer".
This will build your plt file (highly recommend using R15B03 for fast parallel dialyzer)
and run the dialyzer on riak_test. The plt file will only get built once initially, but you can
rebuild it by "make build_plt".

The dialyzer ignore file is a grep expression of warnings to ignore. We need some more,
but this is pretty good start.

And finally the list of "apps" in the dialyzer plt builder needs a few more entries to resolve
those unknown functions. I'm still digging some of those out.

However, we can see a LOT of places where we can clean up the tests based on the output.
See this gist for sample output:

https://gist.github.com/7e4d1ffd55d29b00ba51