Merge branch 'develop' into greenkeeper/scratch-render-0.1.0-prerelease.20181102130522

package.json

src/components/backpack/backpack.css

src/components/backpack/backpack.jsx

src/components/language-selector/language-selector.jsx

src/components/menu-bar/login-dropdown.jsx

src/components/menu-bar/menu-bar.jsx

src/components/menu/menu.jsx

src/components/spinner/spinner.css

src/components/spinner/spinner.jsx

src/components/sprite-selector-item/sprite-selector-item.css

src/components/sprite-selector/sprite-list.jsx

src/containers/backpack.jsx

src/containers/language-selector.jsx

src/containers/sb-file-uploader.jsx

src/containers/sb3-downloader.jsx

src/containers/stage-selector.jsx

src/containers/target-pane.jsx

src/lib/backpack-api.js

src/lib/backpack/block-to-image.js

src/lib/backpack/jpeg-thumbnail.js