Included additional tests from the official V4 test suite.

Added the `get-vanilla-ut8-query` and `post-vanilla-query-space` tests from the current official [Signature Version 4 Test Suite](http://docs.aws.amazon.com/general/latest/gr/signature-v4-test-suite.html).

**Note:** this brings the test suite up to date, *except* that I've **excluded** the following tests for now:
* `get-header-value-multiline.req` test - it has no corresponding `*.{creq,req,sreq,sts}` files, so is of no value, and breaks the `SignatureV4Test::testSuiteProvider` function's 1:5 mapping assumption; and
* `post-vanilla-query-nonunreserved.*` test files - this test fails badly, but frankly the official test looks really broken to me.

Just to be clear, the two tests being excluded were not yet part of the PHP SDK.  This commit is simply adding two tests from the official suite that +are+ valid.

Cheers.

PS - I'd really like to know who to talk to regarding three separate issues I've no found in the official V4 test suite - would love to help getting that suite fixed up :)