Add an onboarding flow (#1452)

* Add an onboarding flow

* Address comments

script/build_frontend

@@ -29,5 +29,5 @@ echo "CREATED_AT = `date +%s`" >> $OUTPUT_DIR_ES5/__init__.py
 # Generate index.htmls with the MD5 hash of the builds
 ./node_modules/.bin/gulp \
     gen-index-html gen-index-html-es5 \
-    gen-authorize-html gen-authorize-html-es5
-
+    gen-authorize-html gen-authorize-html-es5 \
+    gen-onboarding-html gen-onboarding-html-es5

script/develop

@@ -15,5 +15,6 @@ cp -r public/__init__.py $OUTPUT_DIR_ES5/
 
 ./node_modules/.bin/gulp build-translations gen-icons
 cp src/authorize.html $OUTPUT_DIR
+cp src/onboarding.html $OUTPUT_DIR
 
 ./node_modules/.bin/webpack --watch --progress