Fix query parameter handling for pre-signed multipart upload URLs

Fixes #587

Pre-signed requests pertaining to multipart uploads fail on user
account look-up and authentication signature calculation because the
query parameters such as Signature and AWSAccessKeyId are improperly
removed during URL rewriting. Change the rewriting rules so that these
query parameters are not removed and address holes in the unit test
coverage of the S3 URL rewrite module.
Support build_type and backend configuration options

Allow riak_test suites to be run using different backend
configurations and build types.  The backend options are using the
multi_backend in the standard RiakCS setup or the memory backend.  The
build type options are oss or ee and indicates whether an open-source
or enterprise version of Riak should be used for the test run.
Merge branch 'bugfix/presigned-request-authentication' into develop
Merge branch 'feature/riak_test_config_flexibility' into develop