Change yz_security test to determine priv directory via rt:priv_dir
Change riak_test modules to build yz_driver as needed

Change the appropriate riak_test modules to build the yokozuna
basho_bench driver as needed. The driver can still be used for
independent basho_bench testing, but no extra setup is required in
order to run riak_test with the yokozuna tests.
Test updates to avoid nondeterminism in riak_test execution

Changes to avoid some problems with nondeterminism with execution
of the yokozuna riak_test modules.
Update TESTING.md to reflect the update riak_test procedures
Add repo clone instruction to TESTING docs
Use yz_rt:bb_driver_setup for aae_test
Merge pull request #351 from basho/refactor/normalize-riak-test-execution

Normalize riak_test execution process

Reviewed-by: coderoshi
Fix deletion for many-to-one indexing

It is possible to point multiple types and buckets to the same index.
The object key alone is not a unique identifier as the same key could
be repeated across types and buckets.

This patch fixes the deletion code to delete on the actual unique key
which is type + bucket + key.  Other changes made include:

* Expand the essential test to verify deletion and sibling cleanup
  work correctly when using the same key across multiple types and
  buckets.  Add unicode and special chars to additional verification.

* Update the AAE test to to pass the full key when making remote call
  to `yz_solr:delete`.

* Use the ?DEFAULT_TYPE macro in case the default type is changed
  before 2.0.0.

* Change `yz_rt:random_keys` to return binary keys.

* Handle legacy objects (pre 2.0.0) in `encode_delete`.

* Make sure to pass the lager transform when compiling the Yokozuna
  driver and make the `build_bb_driver` function more robust in
  general.