Update ember-dev to publish current build layout.

Details on layout:

https://github.com/emberjs/ember-dev/commit/921dc4ec825917ad5363edbf2213667fd2e9d7ee
Update example serializer so it extends DS.Serializer
Adds note about embedded ids into Transitions doc

I had a time figuring this out myself. `beta1` expects `comments` for
embedded ids instead of `comment_ids`. Although this
is probably going to be changed back in beta2, this change will help
people like me that will update to beta1 before beta2 is out.
Merge pull request #1157 from Floby/patch-1

Update example serializer so it extends DS.Serializer
Merge pull request #1151 from kurko/add_note_about_embedded_ids_into_transitions_doc

Adds note about embedded ids into Transitions doc
Merge pull request #1156 from rjackson/update_ember-dev

Update ember-dev to publish current build layout.
Add info about JSON Transformers to TRANSITION.md
Update README.md
Fixed what appered to be trivial typos in the Serializer Configuration examples
containerization of transforms
added content from latest merge
Merge pull request #1162 from ghempton/containerize-transforms

containerization of transforms
Add support for since token in meta
Fix rollback from new state (unload record)

Add more rollback tests
Add support for key normalization in RESTAdapter
Merge pull request #1166 from tchak/rollback-tests

Fix rollback from new state (unload record)
Fixes typo
Merge pull request #1164 from joebartels/master

fix small typos in TRANSITION.md
Merge pull request #1167 from johanneswuerbach/patch-1

Fixes typo
Merge pull request #1160 from jagthedrummer/jeremy/transition-transforms

Add info about JSON Transformers to TRANSITION.md