Add Ember.computed.none… none + empty have different secants.

Also extract Ember.isNone into ember-metal

packages/ember-metal/lib/computed.js

@@ -429,6 +429,18 @@ Ember.computed.not = function(dependentKey) {
   });
 };
 
+/**
+  @method computed.none
+  @for Ember
+  @param {String} dependentKey
+*/
+Ember.computed.none = function(dependentKey) {
+  return Ember.computed(dependentKey, function(key) {
+    var val = get(this, dependentKey);
+    return Ember.isNone(val);
+  });
+};
+
 /**
   @method computed.empty
   @for Ember

packages/ember-metal/lib/core.js

@@ -228,6 +228,31 @@ Ember.merge = function(original, updates) {
     original[prop] = updates[prop];
   }
 };
+
+/**
+  Returns true if the passed value is null or undefined. This avoids errors
+  from JSLint complaining about use of ==, which can be technically
+  confusing.
+
+  ```javascript
+  Ember.isNone();              // true
+  Ember.isNone(null);          // true
+  Ember.isNone(undefined);     // true
+  Ember.isNone('');            // false
+  Ember.isNone([]);            // false
+  Ember.isNone(function(){});  // false
+  ```
+
+  @method isNone
+  @for Ember
+  @param {Object} obj Value to test
+  @return {Boolean}
+*/
+Ember.isNone = function(obj) {
+  return obj === null || obj === undefined;
+};
+Ember.none = Ember.deprecateFunc("Ember.none is deprecated. Please use Ember.isNone instead.", Ember.isNone);
+
 /**
   Verifies that a value is `null` or an empty string, empty array,
   or empty function.

packages/ember-runtime/lib/core.js

@@ -83,29 +83,6 @@ Ember.typeOf = function(item) {
 };
 
 /**
-  Returns true if the passed value is null or undefined. This avoids errors
-  from JSLint complaining about use of ==, which can be technically
-  confusing.
-
-  ```javascript
-  Ember.isNone();              // true
-  Ember.isNone(null);          // true
-  Ember.isNone(undefined);     // true
-  Ember.isNone('');            // false
-  Ember.isNone([]);            // false
-  Ember.isNone(function(){});  // false
-  ```
-
-  @method isNone
-  @for Ember
-  @param {Object} obj Value to test
-  @return {Boolean}
-*/
-Ember.isNone = function(obj) {
-  return obj === null || obj === undefined;
-};
-Ember.none = Ember.deprecateFunc("Ember.none is deprecated. Please use Ember.isNone instead.", Ember.isNone);
-
  This will compare two javascript values of possibly different types.
  It will tell you which one is greater than the other by returning: