Dialyzer Cleanup

[beerriot]

Major thanks to @kostis, @cmeiklejohn, and @andrewjstone for sitting with me last week and plowing through Dialyzer's complaints about riak_pipe. This PR fixes the things we found:

• incorrect types - mostly switching from non-exported things to exported things, but also a little refactoring to make code cleaner and not rely on non-exported types
• unmatched returns - often just being explicit about not caring what a return value is, but also many cases where functions should have failed if calls didn't return success (mostly in testing code, but good to have our tests be pickier)
• missing function parameters - just a completely incorrect call that might have been exploding

All eunit tests pass all pipe* and mapred* riak_test cases pass locally for me, except mapred_basic_compat, which is known broken currently.

[cmeiklejohn]

@beerriot Can we add the updated rebar to this repo? Eunit passes, but I can't run Dialyzer standalone on the repository because the version of rebar included doesn't correctly handle the protobuffs dependency.

dialyzer: Could not get abstract code for file: /Users/cmeiklejohn/Repositories/riak_pipe/deps/riak_core/ebin/riak_core_pb.beam 
(please recompile it with +debug_info)

[beerriot]

@cmeiklejohn That's odd. That's what commit 8b24edb did. That version worked for me with R16B02.

[cmeiklejohn]

I hope you don't mind, but I've also added a couple commits to this branch:

b1248ff465bd4e2030abc207d0fa25dcfec0ffcd, which ensures that the compile target depends on the dependencies target c1aa0e6d9319c2f07ea1335f36bd3c6fac3ba651, only run Dialyzer on the riak_pipe application

Also, I've rebuild all deps from scratch and was able to run the Dialyzer without issue.

:+1:

[beerriot]

Excellent, thanks @cmeiklejohn!