Remove StringValue calls from match.c

These calls were probably always overly defensive (for example, the
`needle` already gets submitted to a StringValue call by the caller, and
the `str` value is effectively always a string because the scanners
consistently provide strings; if they didn't, exceptions would be being
thrown here).

So, this is an unnecessary guard, but another reason why it's worth
getting rid of is that it involves touching the Ruby runtime (it's a
macro which expands to several nested function calls, in which it is
possible that exceptions can be raised; see string.c and object.c in the
Ruby source tree) which is considered unsafe in a threaded environment.

If my assumptions here prove to be incorrect, we can always add back
some explicit "String-ness" enforcement, but if we do have to do that,
we'll do it at the Scanner level.

One thing to note: I was hoping that this might give us an infinitesimal
speed-up, seeing as we're doing ever so slightly less work now, but the
benchmarks show that there is no measurable difference.

Signed-off-by: Wincent Colaiuta <win@wincent.com>
Update docs for 1.6 release

Signed-off-by: Wincent Colaiuta <win@wincent.com>
Reformat HISTORY section to make it parseable again

The `prepare_release_notes` method in the Rakefile requires a blank line
after each "heading". It's possible that this is too strict, but I'm
going to leave it as-is for now.

Signed-off-by: Wincent Colaiuta <win@wincent.com>
Apply temporary hack to get AWS uploads working

Much as I did in the Clipper repo:

  https://wincent.com/repos/clipper/commits/935c05aea52971ea1a3bab4337cffc5f0e3f344e

Here we apply a hack to get the `aws` tool uploading for the 1.6
release.

Signed-off-by: Wincent Colaiuta <win@wincent.com>