component/nginx: Add support for SPDY and gzip_static

Both SPDY an gzip_static are needed for upcoming GitLab SR:

  - GitLab uses SPDY in its https nginx configuration, and
  - prepares compiled assets in pre-gzipped form on filesystem

both modules are off by default and need to be explicitly enabled with
corresponding directives, so this should not affect already used nginx
configurations.

/cc @kazuhiko, @jerome, @gabriel
/reviewed-by @rafael  (on nexedi/slapos!30)

component/nginx/buildout.cfg

@@ -19,6 +19,8 @@ md5sum = 27322fbb4b265c0e0cc548f5e6b7f201
 configure-options=
   --with-ipv6
   --with-http_ssl_module
+  --with-http_spdy_module
+  --with-http_gzip_static_module
   --with-mail
   --with-mail_ssl_module
   --with-ld-opt="-L ${openssl:location}/lib -L ${pcre:location}/lib -L ${zlib:location}/lib -Wl,-rpath=${openssl:location}/lib -Wl,-rpath=${pcre:location}/lib -Wl,-rpath=${zlib:location}/lib"
@@ -36,6 +38,8 @@ mode = 0644
 configure-options =
   --with-ipv6
   --with-http_ssl_module
+  --with-http_spdy_module
+  --with-http_gzip_static_module
   --with-mail
   --with-mail_ssl_module
   --error-log-path=var/log/nginx.error.log