Allow Blueprints to add packages to projects package.json.

* Add `Blueprint.prototype.addPackageToProject`.
* Add slow smoke test to confirm `ember g http-proxy` adds packages.
* Removes unneeded packages from ember-cli's package.json.
Merge pull request #1598 from rwjblue/allow-blueprints-to-add-packages

Allow Blueprints to add packages to projects package.json.
Deprecate --proxy option.
[BUGFIX] new with --dry-run does not create new directory

fixes #1592
Merge pull request #1603 from rwjblue/deprecate--proxy

Deprecate --proxy option.
Merge pull request #1602 from fivetanley/new-with-dry-run-fix

new with —dry-run does not create new directory
Allow test suite to run in full
Merge pull request #1605 from bcardarella/bc-remove-only

Allow test suite to run in full
Fix EmberAddon vendor tree
Merge pull request #1606 from bcardarella/bc-addon-vendor-tree-fix

Fix EmberAddon vendor tree
Addon blueprint

Generates a skeleton project for addons
Merge pull request #1374 from bcardarella/bc-addon-blueprint

Addon blueprint
Refactor addon command to inherit from new.

Removes duplication.
Fix addon package

Closes #1610
Merge pull request #1611 from bcardarella/bc-fix-addon-package

Fix addon package
Merge pull request #1609 from rwjblue/git-init-in-addon

Refactor addon command to inherit from new.
Adds some lines to the README about a common issue on Ubuntu
Merge pull request #1613 from nick-lehmann/master

Adds some lines to the README about a common issue on Ubuntu
fix typo
Merge pull request #1614 from jakecraige/patch-3

fix typo