Don't dirty records if value doesn't change

When setting an attribute on a record, the record
should only be marked dirty if the value being
set is different from the old value.

NB: Because we are comparing the serialized
values, so long as the values serialize to the
same string, they will be considered equal.
Update Ember
Fix ambiguity that used to work but shouldn't
More advanced FixtureAdapter implementation
Make async helper global to tests
Clean up Ember.Application integration test
Update master
Add `has` method to find out if a record with a given id is loaded

Alias `has` method on the model class
Merge pull request #321 from tchak/has-records

Add `has` method to find out if a record with a given id is loaded
has -> recordIsLoaded
Merge pull request #309 from tchak/fixtures

More advanced FixtureAdapter implementation
Merge pull request #323 from tchak/has-records

has -> recordIsLoaded
fix failing test in fixture adapter
Merge pull request #324 from tchak/fixtures

fix failing test in fixture adapter
Use set for updating errors object - Fixes #314
Merge pull request #311 from MilkyWayJoe/patch-1

Correct mistake in README.
Added build instructions - Fixes #290
Refactor upload_latest task to use github_downloads gem
Merge pull request #328 from pangratz/update_uploader

Refactor upload_latest task to use github_downloads gem
Prep for moving waitingOn to adapter

This commit starts us down the path of moving the
logic for pending/waitingOn into the adapter.