Warn if an application lacks a Store property

Attempts to use model class related methods that alias
to the store currently throw
`TypeError: Cannot read property 'find' of undefined`

This commit improves the message and offers a suggested
solution.
Fixed trailing commas which breaks IE7.
Warn, don't fail, when there are no fixtures
Fail rather than returning all fixtures when queryFixtures is not implemented
Use Ember.run.later instead of setTimeout in FixtureAdapter
Be asynchronous (though deterministic) when simulateRemoteResponse is false

It's not clear that there is really a use case for synchronous responses
in FixtureAdapter. Asynchronous responses on the other hand are much
preferable for realistic testing.
Merge pull request #744 from CrowdStrike/fixture-adapter

Fixture adapter
Merge pull request #700 from airportyh/fix_trailing_commas_ie7

Fixed trailing commas which breaks IE7.
Merge pull request #707 from CrowdStrike/missing-fixtures

Warn, don't fail, when there are no fixtures
Merge pull request #706 from CrowdStrike/query-fixtures

Fail rather than returning all fixtures when queryFixtures is not implemented
Merge pull request #689 from trek/improve-error-message-for-missing-store

Warn if an application lacks a Store property
creating a new branch and just updating the https to see if that will not cause the Travis build to fail

add https to Gemfile.lock
Merge pull request #757 from cgcardona/gemfile_update

Updating `source` in Gemfile to point to `https`
removed vendored handlebars, gemified ember-data. no longer test with
jQuery 1.7 since hasn't been compatible with Ember for a while
Fix typo in the comment on Primary key overriding options
Merge pull request #761 from machty/gemified

removed vendored handlebars, gemified ember-data. no longer test with
Merge pull request #765 from dybskiy/master

Fix typo in the comment on Primary key overriding options
Added support for polymorphic associations.

App.User = DS.Model.extend({
 messages: DS.hasMany(App.Message, {polymorphic: true})
});

App.Message = DS.Model.extend({
  created_at: DS.attr('date'),
  user: DS.belongsTo(App.User)
});

App.Post = App.Message.extend({
  title: DS.attr('string')
});

App.Comment = App.Message.extend({
  body: DS.attr('string'),
  message: DS.belongsTo(App.Message, {polymorphic: true})
});

You need to configure the serializer to map to the correct type:

DS.RESTAdapter.configure('App.Post' {
  alias: 'post'
});
DS.RESTAdapter.configure('App.Comment' {
  alias: 'comment'
});

Initializing an alias will automatically allow you to sideload this
type. The support for sideloadAs is only for backward compatibility.

Embedded polymorphic associations are not supported yet.
Added support for embedded polymorphic associations