[BUGFIX beta] ember-routing: Always inherit model from parent
Allow development only feature flags.

When a flag with `development-only` is found in `features.json` it will
be enabled (flags stripped) for `ember.js`, and disabled (flags
stripped) for `ember.prod.js`.
Fix argument order for handleMandatorySetter.
Use separate FEATURES for dev vs prod builds.
Use `ember-tests.prod.js` when testing prod builds.
Merge pull request #5532 from rwjblue/allow-production-only-feature-flags

Allow development only feature flags.
Merge pull request #5610 from ef4/always-inherit

Fix ember-routing-inherits-parent-model for nestable routes.
Test optional features in production builds.
[FEATURE ember-metal-injected-properties] Ensure tests work in prod builds.
Merge pull request #5618 from rwjblue/run-feature-tests-in-prod

Ensure optional features are tested against production builds.
[BUGFIX release] Cleanup ES3 Object.keys
[BUGFIX release] fix finishChains for all chains that reference an obj not just the ones rooted at that object.
Merge pull request #5575 from krisselden/fix-finish-chains

[BUGFIX release] Fix finishChains
Adding dir and lang to allow for easier bidirectional support
Merge pull request #5634 from chadhietala/add-dir-lang

Adding dir & lang attribute bindings to allow for easier bidirectional support