Support SCRIPT_NAME in MiniProfiler

Currently MiniProfiler ignores SCRIPT_NAME in Rack, which prevents apps running at relative paths (like '/myapp') from serving the JS or responding to the core requests.  This pull prefixes @config.base_url_path with env['SCRIPT_NAME'] when serving the JS append and when serving results - serving links to '/myapp/mini-profiler-resources/...'.

Commit includes a failing test.