console: support /pagespeed_console

sligocki is adding a feature to pagespeed where it will parse your statistics
for you and determine if there are any problems.  This CL wires up the
ConsoleHandler and also includes a few required files in the build process.

It doesn't work yet, because as of svn r3193 the console has a hardcoded json
request to '/mod_pagespeed_statistics' and in nginx we use '/ngx_...' .
I've tested this by changing all uses here to use the "mod_..." version and that
worked, but I've undone those changes.

test/pagespeed_test.conf.template

@@ -39,6 +39,10 @@ http {
   # critical images to be inlined, so we just disable the option here.
   pagespeed CriticalImagesBeaconEnabled false;
 
+  pagespeed Statistics on;
+  pagespeed StatisticsLogging on;
+  pagespeed LogDir "@@TEST_TMP@@/logdir";
+
   server {
     # Sets up a logical home-page server on
     # max-cacheable-content-length.example.com.  This server is only used to
@@ -104,7 +108,7 @@ http {
       set $ua_dependent_ps_capability_list "";
       set $bypass_cache 1;
     }
-    
+
     location ~ /purge(/.*) {
       allow all;
       proxy_cache_purge htmlcache $ua_dependent_ps_capability_list$1$is_args$args;