Move most of code for getting latest tag/version and calling publish_release to postpublish_utils script in top-level dir

scripts/postpublish_utils.js

@@ -0,0 +1,47 @@
+const execAsync = require('async-child-process').execAsync;
+const semverSort = require('semver-sort');
+const promisify = require('es6-promisify');
+const publishRelease = require('publish-release');
+
+const publishReleaseAsync = promisify(publishRelease);
+const githubPersonalAccessToken = process.env.GITHUB_PERSONAL_ACCESS_TOKEN_0X_JS;
+
+module.exports = {
+    getLatestTagAndVersionAsync: function(subPackageName) {
+        const subPackagePrefix = subPackageName + '@';
+        const gitTagsCommand = 'git tags -l "' + subPackagePrefix + '*"';
+        return execAsync(gitTagsCommand)
+            .then(function(result) {
+                if (result.stderr !== '') {
+                    throw new Error(result.stderr);
+                }
+                const tags = result.stdout.trim().split('\n');
+                const versions = tags.map(function(tag) {
+                    return tag.slice(subPackagePrefix.length);
+                });
+                const sortedVersions = semverSort.desc(versions);
+                const latestVersion = sortedVersions[0];
+                const latestTag = subPackagePrefix + latestVersion;
+                return {
+                    tag: latestTag,
+                    version: latestVersion
+                };
+            });
+    },
+    publishReleaseNotes: function(tag, releaseName, assets) {
+        console.log('POSTPUBLISH: Releasing ', releaseName, '...');
+        return publishReleaseAsync({
+            token: githubPersonalAccessToken,
+            owner: '0xProject',
+            repo: '0x.js',
+            tag: tag,
+            name: releaseName,
+            notes: 'TODO',
+            draft: false,
+            prerelease: false,
+            reuseRelease: true,
+            reuseDraftOnly: false,
+            assets: assets,
+         });
+    },
+};