Renamed model errors key from _ to __model

As discussed on IRC. Also add task for 2.0 to change the validate()
output structure.

README.md

@@ -77,6 +77,9 @@ A very basic roadmap. Chances aren't too bad, that not mentioned things are impl
 - ~~save datetimes in UTC~~
 - encapsulate attributes if a dao inside the attributes property + add getters and setters
 - add proper error message everywhere
+- refactor validate() output data structure, separating field-specific errors
+  from general model validator errors (i.e.
+  `{fields: {field1: ['field1error1']}, model: ['modelError1']}` or similar)
 
 
 ## Collaboration 2.0 ##

lib/dao.js

@@ -276,10 +276,10 @@ module.exports = (function() {
       try {
         validator.apply(self)
       } catch (err) {
-        if (!failures.hasOwnProperty('_')) {
-          failures._ = []
+        if (!failures.hasOwnProperty('__model')) {
+          failures.__model = []
         }
-        failures._.push(err.message)
+        failures.__model.push(err.message)
       }
     })
 

spec/dao.validations.spec.js

@@ -330,7 +330,7 @@ describe(Helpers.getTestDialectTeaser("DAO"), function() {
       var failingFoo = Foo.build({ field1: null, field2: null })
         , errors     = failingFoo.validate()
       expect(errors).not.toBeNull()
-      expect(errors).toEqual({ '_': ['xor failed'] })
+      expect(errors).toEqual({ '__model': ['xor failed'] })
 
       var successfulFoo = Foo.build({ field1: 33, field2: null })
       expect(successfulFoo.validate()).toBeNull()