Nginx improvements

Add a server_names_hash_bucket_size directive during challenges to fix an nginx
crash on restart (Fixes #922).

Use fullchain instead of chain (Fixes #610).

Implement OCSP stapling (Fixes #937, Fixes #931).

Hide Boulder output in integration tests to make them more readable.

letsencrypt-nginx/tests/boulder-integration.conf.sh

@@ -20,7 +20,6 @@ events {
 }
 
 http {
-  server_names_hash_bucket_size 2048;
   # Set an array of temp and cache file options that will otherwise default to
   # restricted locations accessible only to root.
   client_body_temp_path $root/client_body;