Default to current working directory
Version bump.

This commit is the top of a series of commits that have done significant
refactoring to rack-legacy. Some highlights:

* By using PHP's built-in web server (as first suggested by @nazgu1) the
  performance is much better. In addition to no longer booting up PHP on
  every request (which saves a lot of time) it also allows PHP to cache
  things like database connection and code compiles. Just running a dummy
  PHP file (i.e. echo 'ok';) was *over 500 times faster*.
* The CGI handling was refactored a bit using `childprocess` gem that is
  being used for the new PHP code. This greatly simplified the CGI code also.
* The PHP module had support for serving up index.php if a directory was
  requested. This has been replaced with Rack::Legacy::Index which is more
  flexible and gets rid of the need for the rack-rewrite mess
  [some people were doing](http://stuff-things.net/2011/05/16/legacy-development-with-pow/)