Fix order of arguments passed to `yz_kv:dont_index`

This patch addresses a seemingly trivial dialyzer warning:

```
yz_kv.erl:182: The call
yz_kv:dont_index(Obj::riak_object:riak_object(),Reason::any(),P::non_neg_integer(),ShortPL::{non_neg_integer(),pos_integer()},BKey::{binary(),binary()})
breaks the contract (obj(),write_reason(),p(),bkey(),short_preflist())
-> 'ok'
```

What this warning is saying is that 2 of the arguments to the
`dont_index` function were switched. The `bkey()` and
`short_preflist()` arguments. This means that any time KV data was
written to a bucket without an index associated with it the YZ AAE
trees were not getting updated with the KV hash. This is bad because
without those hashes YZ AAE will constantly think that it is missing
postings for KV data and will invoke repiar for every single KV object
written to any non-indexed bucket. When the repair function is invoked
it will add the missing hash but this would still create a lot of
superfluous repairs while writing non-indexed data.

The fix is simple. Switch the two arguments. Along with the fix I also
added a test to `aae_test` to catch any future regressions.
Merge pull request #285 from basho/rz/bugfix/no-repair-non-indexed

Fix order of arguments passed to `yz_kv:dont_index`