Create a post-process step to transform search page

[joeytakeda]

In #251, we were talking about changing fieldsets, but talking it through, we determined that it may be best to give more flexibility for post-processing the search page (we do it for the majority of our projects anyway). So what we're thinking is:

• A configuration element that points to an XSL file (relative to the configuration file) that would post-process the search HTML page
• In the search configuration page, we add the XSL path as a parameter and then using fn:transform to transform the result of the search page, if necessary.
• We provide a sample one that changes fieldsets to <details> since that's a common modification

[martindholmes]

We should actually build this into our test suite, so we can be sure it works on Windows etc., and take advantage of it to pretty-up the test results a bit perhaps.