delete extract dir before extraction

package.json

@@ -14,7 +14,7 @@
         "build:stable": "rimraf build/stable && npx webpack --config webpack/production.babel.js --output-path build/stable --progress --bail",
         "build:beta": "rimraf build/beta && cross-env BUILD=beta npx webpack --config webpack/production.babel.js --output-path build/beta --progress --bail",
         "build:dev": "rimraf build.dev && cross-env BUILD=development npx webpack --config webpack/production.babel.js --output-path build/dev --progress --bail",
-        "translations:extract": "cross-env NODE_ENV=translations babel src",
+        "translations:extract": "rimraf translations/extractedMessages && cross-env NODE_ENV=translations babel src",
         "translations:sync": "yarn ttm merge-msgs && yarn ttm build-csv && yarn ttm upload && yarn ttm build-translations && yarn ttm export-translations",
         "flow": "flow check src",
         "lint": "run-s lint:*",