6.0.0

I'm extremely stupid and didn't commit as I go. To anyone reading this
I'm extremely sorry. A lot of these changes are very broad and I plan on
releasing Babel 6.0.0 today live on stage at Ember Camp London so I'm
afraid I couldn't wait. If you're ever in London I'll buy you a beer
(or assorted beverage!) to make up for it, also I'll kiss your feet and
give you a back massage, maybe.

test/fixtures/esprima/es2015-destructuring-assignment-array-pattern/nested-cover-grammar/expected.json

@@ -88,7 +88,7 @@
                 },
                 "properties": [
                   {
-                    "type": "Property",
+                    "type": "ObjectProperty",
                     "start": 2,
                     "end": 5,
                     "loc": {
@@ -120,7 +120,6 @@
                       },
                       "name": "a"
                     },
-                    "kind": "init",
                     "value": {
                       "type": "AssignmentPattern",
                       "start": 2,