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.
This change looks a bit scary.  Granted, the original `wait_until(_, 0, _)` should probably have checked for negative values of `Retry`, but that seems less likely than somehow getting called with `Retry == 0`, which would be very bad.