Add riak_test to Dialyzer.
Updated makefile.
Refactoring for clarity.
Add threshold read.

Add a threshold read primitive to derflow with a test to ensure
correct behavior.  Register waiting processes with a threshold, so
notifications are only delivered when the threshold is met or passed.
Resolve dialyzer warnings.
Resolve incorrect threshold match.

Resolve an incorrect pattern match with the threshold read operation
where it will incorrectly match the threshold and fail to terminate.
Convert nil to undefined.

Convert nil to undefined to be closer to OTP.
Update test to assert.

Update the test to actually assert on the value.
Remove read process tracking.

Remove the read process tracking code which re-executes processes that
perform read operations when lattices change.