slt: add shrinkwrap cmd for filtering fields

When using shrinkwrap, combined with a private staging registry, you may
not want your internal registry's URLs baked in to the
npm-shrinkwrap.json file that gets created. This utility strips out
those fields.

index.js

@@ -14,4 +14,5 @@ module.exports = {
   version: require('./lib/version'),
   semver: wrapped('semver/bin/semver'),
   copyright: require('./lib/copyright'),
+  shrinkwrap: require('./lib/shrinkwrap'),
 };

lib/shrinkwrap.js

@@ -0,0 +1,46 @@
+// Copyright IBM Corp. 2016. All Rights Reserved.
+// Node module: strong-tools
+// This file is licensed under the MIT License.
+// License text available at https://opensource.org/licenses/MIT
+
+'use strict';
+
+var _ = require('lodash');
+var assert = require('assert');
+var debug = require('debug')('strong-tools:fix-license');
+var json = require('json-file-plus');
+var path = require('path');
+
+updateShrinkwrap.out = console.log;
+exports.cli = updateShrinkwrap;
+
+function updateShrinkwrap(shrinkwrap) {
+  shrinkwrap = path.resolve(shrinkwrap || 'npm-shrinkwrap.json');
+  debug(shrinkwrap);
+
+  updateShrinkwrap.out('removed resolution URLs from %s', shrinkwrap);
+
+  return json(shrinkwrap).catch(function(err) {
+    assert.ifError(err, 'Failed to open ' + shrinkwrap + ': ' + shrinkwrap);
+  }).then(rewrite).catch(function(err) {
+    assert.ifError(err, 'Failed to filter out "resolved" from ' + shrinkwrap);
+  });
+
+  function rewrite(file) {
+    removeResolved(file.data);
+    updateShrinkwrap.out('removed resolution URLs from %s', shrinkwrap);
+    return file.save();
+
+    // XXX(rmg): this is recursive, but the tree should not be too deep
+    function removeResolved(obj, k) {
+      if (_.isObjectLike(obj)) {
+        // only removed resolved key when the value is a string, otherwise
+        // we're basically blacklisting any use of the module named "resolved"
+        if (_.isString(obj.resolved)) {
+          delete obj.resolved;
+        }
+        _.each(obj, removeResolved);
+      }
+    }
+  }
+}