Refactor common AAE test code and add custom N test.
* Common code in the cluster setup and data setup is factored out into a utility module.
* AAE fullsync test and benchmark get skinnier and call the common setup code.
* Document parameters in the setup for tests.
* Add a new AAE fullsync test that changes the N value (source is 2, sink is 3).
Updated documentation; this test is expected to fail.
Test for differing n_val for AAE fullsync should now pass.
Reduce keycount to something reasonable for a riak_test
Merge pull request #289 from basho/cet-aae-refactor

Cet aae refactor