Upgrade vulcanize to 0.7.6.

node_modules/vulcanize/node_modules/update-notifier/node_modules/semver-diff/node_modules/semver/semver.js

Index: node_modules/vulcanize/node_modules/update-notifier/node_modules/semver-diff/node_modules/semver/semver.js
diff --git a/node_modules/vulcanize/node_modules/update-notifier/node_modules/semver-diff/node_modules/semver/semver.js b/node_modules/vulcanize/node_modules/update-notifier/node_modules/semver-diff/node_modules/semver/semver.js
index 22673fdd1937d40ad5a0159e33a3647ccda6a1eb..026173eabcde4522c2ef4f0bec506ff08cfe6fe2 100644
--- a/node_modules/vulcanize/node_modules/update-notifier/node_modules/semver-diff/node_modules/semver/semver.js
+++ b/node_modules/vulcanize/node_modules/update-notifier/node_modules/semver-diff/node_modules/semver/semver.js
@@ -464,6 +464,33 @@ function inc(version, release, loose, identifier) {
   }
 }
 
+exports.diff = diff;
+function diff(version1, version2) {
+  if (eq(version1, version2)) {
+    return null;
+  } else {
+    var v1 = parse(version1);
+    var v2 = parse(version2);
+    if (v1.prerelease.length || v2.prerelease.length) {
+      for (var key in v1) {
+        if (key === 'major' || key === 'minor' || key === 'patch') {
+          if (v1[key] !== v2[key]) {
+            return 'pre'+key;
+          }
+        }
+      }
+      return 'prerelease';
+    }
+    for (var key in v1) {
+      if (key === 'major' || key === 'minor' || key === 'patch') {
+        if (v1[key] !== v2[key]) {
+          return key;
+        }
+      }
+    }
+  }
+}
+
 exports.compareIdentifiers = compareIdentifiers;
 
 var numeric = /^[0-9]+$/;