gyp: link with dring

Change-Id: Ie93c667900205a3fc756707cd2bde6174202f805

bin/nodejs/binding.gyp

@@ -4,6 +4,7 @@
       "target_name": "dring",
       "sources": [ "ring_wrapper.cpp" ],
       'include_dirs': ['../../src/'],
+      'libraries': ['-L../../src/.libs/', '-lring'],
       'cflags!': [ '-fno-exceptions' ],
       'cflags_cc!': [ '-fno-exceptions' ]
     }