Backport relevant 2.0 repl tests

Some riak tests in 2.0 are relevant to the 1.4.12 release.  So far I have added repl_fs_stat_caching, since stat caching was backported by @jonmeredith to 1.4. Also, repl_location_failures is good since the AAE fullsync noisy logs PR touched that code. In fact, this PR shows there is a problem with the AAE fullsync noise reduction: the error and retry exit counts are broken when location_down messages are received when partition is not available.
Isn't this second iteration redundant?
If every Node of P1 is partitioned from every Node of P2, does it not hold that every Node of P2 is partitioned from every Node of P1?