simplify riak_pipe_builder_sup:builder_pids return value

This removes the use of types not exported from 'supervisor' while also making
the return value match the name of the function.
refactor riak_pipe_state:do_update to only return ok

this resolves a dialyzer error, and also makes it clearer what uses the monitor
use erlang:timestamp type instead of unexported calendar:t_now
fix type of riak_pipe_vnode:reply_to_blocker

riak_core_vnode:reply mimics various erlang message sending functions, which means
some return 'true', but others return the message that was sent, so the type for
this function must be any()
correct unmatched return values

dialyzer found many places where the return values of functions were ignored

this commit adds failing matches or don't-care matches where appropriate
change if to case so dialyzer can understand it

The logic before and after this commit should be exactly the same, but dialyzer
reports the following for the `if` version:

"riak_pipe_builder.erl:206: Clause guard cannot succeed."

three out of four developers prefer the `case` version anyway
update rebar to same as riak repo, so riak_core_pb can be dialyzered
remove incorrect dialyzer.ignore-warnings
add index to call to riak_core_ring:index_owner

dialyzer complained about riak_core_ring:index_owner/1 not existing,
because it's index_owner/2 and the Index argument was missing here
Ensure that compile has a dependency on the deps.
Only dialyze the current application.
Merge PR #79 from branch 'refactor/bwf/dialyzer' into develop