Update to C++14 as required by Cap'n Proto 0.7.

binding.gyp

@@ -4,12 +4,12 @@
       'target_name': 'capnp',
       'sources': ['src/node-capnp/capnp.cc'],
       'libraries': ['-lkj', '-lkj-async', '-lcapnp', '-lcapnpc', '-lcapnp-rpc'],
-      'cflags_cc': ['-std=c++11'],
+      'cflags_cc': ['-std=c++14'],
       'cflags_cc!': ['-fno-rtti', '-fno-exceptions'],
       'conditions': [
         [ 'OS=="mac"', {
           'xcode_settings': {
-            'OTHER_CPLUSPLUSFLAGS' : ['-std=c++11','-stdlib=libc++'],
+            'OTHER_CPLUSPLUSFLAGS' : ['-std=c++14','-stdlib=libc++'],
             'OTHER_LDFLAGS': ['-stdlib=libc++'],
             'GCC_ENABLE_CPP_RTTI': 'YES',
             'GCC_ENABLE_CPP_EXCEPTIONS': 'YES',