added model common plugin, added components to readme

@@ -25,6 +25,19 @@ eskimo --help
 ```
 
 
+## Components
+
+Using `electrolyte`, you an inject the following dependencies into your app with `eskimo`:
+
+* `app` - returns an instance of `express()`
+* `error-handler` - returns an error handler that can be used via `app.use`
+* `db` - returns connection to MongoDB
+* `logger` - returns a Winston logger instance
+* `model-common-plugin` - returns a Mongoose plugin for common schema paths
+* `sessions` - returns connection to Redis
+* `settings` - returns config
+
+
 ## Contributors
 
 * Nick Baugh <niftylettuce@gmail.com>

+
+// # boot - model common plugin
+
+var _ = require('underscore')
+var jsonSelect = require('mongoose-json-select')
+
+exports = module.exports = function(settings) {
+
+  return function(Schema) {
+
+    // NOTE: To allow `.sort('-created_at')` to work
+    // we need to have these as actual paths
+    Schema.add({
+      updated_at: Date,
+      created_at: Date
+    })
+
+    Schema.pre('save', function(next) {
+
+      var that = this
+
+      that.updated_at = (!that.created_at) ? Date.now() : that._id.getTimestamp()
+
+      if (!that.created_at)
+        that.created_at = that._id.getTimestamp()
+
+      // version history (alternative to `mongoose-version` and `mongoose-history`)
+      if (settings.mongooseVersioning) {
+        var version = that.toObject()
+        version.__v = _.isNumber(version.__v) ? version.__v + 1 : 0
+        delete version.__versions
+        that.__versions.push(version)
+      }
+      next()
+    })
+
+    Schema.set('toObject', {
+      virtuals: true,
+      getters: true
+    })
+
+    Schema.set('toJSON', {
+      virtuals: true,
+      getters: true
+    })
+
+    Schema.plugin(jsonSelect, '-_id -__v')
+
+    return Schema
+
+  }
+
+}
+
+exports['@singleton'] = true
+exports['@require'] = [ 'settings' ]