Adds a migration script to fix bad dates

Finds all dates that have a space in them (implying they are the
problematic "17th Apr, 2010" style) and convert them to YYYY-MM-DD as
expected.

Issue: medic/cht-core#1672

migrations/convert-bad-dob-format.js

@@ -0,0 +1,38 @@
+var async = require('async'),
+    db = require('../db'),
+    moment = require('moment');
+
+var temporaryView = {
+  "map": "function(doc) { if (doc.type === 'person' && doc.date_of_birth && doc.date_of_birth.indexOf(' ') >= 0) { emit(1); }}"
+};
+
+module.exports = {
+  name: 'convert-bad-dob-format',
+  created: new Date(2016, 4, 20),
+  run: function(callback) {
+    db.request({
+      db: 'medic',
+      method: 'POST',
+      path: '_temp_view',
+      body: temporaryView,
+      qs: {
+        include_docs: true,
+      }
+    }, function(err, result) {
+      var docs = result.rows.map(function(row) {
+        return row.doc;
+      });
+
+      for(doc of docs) {
+        var currentDob = doc.date_of_birth;
+        var convertedDob = moment(doc.date_of_birth, 'MMM Do, YYYY').format('YYYY-MM-DD');
+
+        doc.date_of_birth = convertedDob;
+      }
+
+      db.medic.bulk({
+        docs: docs
+      }, callback);
+    });
+  }
+};