refact(input): split input.js into smaller files

The input.js file is unnecessarily large, containing many directives including the
vast `ngModel`. This change moves ngModel and a few other directives into their
own files, which will make maintenance easier.

angularFiles.js

@@ -53,6 +53,7 @@ var angularFiles = {
     'src/ng/directive/form.js',
     'src/ng/directive/input.js',
     'src/ng/directive/ngBind.js',
+    'src/ng/directive/ngChange.js',
     'src/ng/directive/ngClass.js',
     'src/ng/directive/ngCloak.js',
     'src/ng/directive/ngController.js',
@@ -61,6 +62,8 @@ var angularFiles = {
     'src/ng/directive/ngIf.js',
     'src/ng/directive/ngInclude.js',
     'src/ng/directive/ngInit.js',
+    'src/ng/directive/ngList.js',
+    'src/ng/directive/ngModel.js',
     'src/ng/directive/ngNonBindable.js',
     'src/ng/directive/ngPluralize.js',
     'src/ng/directive/ngRepeat.js',
@@ -70,7 +73,8 @@ var angularFiles = {
     'src/ng/directive/ngTransclude.js',
     'src/ng/directive/script.js',
     'src/ng/directive/select.js',
-    'src/ng/directive/style.js'
+    'src/ng/directive/style.js',
+    'src/ng/directive/validators.js'
   ],
 
   'angularLoader': [