fix building all frameworks

Author: krausest

README.md

@@ -142,6 +142,10 @@ This installs just a few top level dependencies for the building the frameworks
 ```
 npm ci
 ```
+Then install the server:
+```
+npm run install-server
+```
 
 We start the local web server in the root directory
 

rebuild-all.js

@@ -47,8 +47,7 @@ const filesToDelete = [
   "bower_components",
   "node_modules",
   "output",
-  useCi && "package-lock.json",
-].filter(Boolean);
+].concat(useCi ? [] : ["package-lock.json"]);
 
 /**
  * @typedef {Object} Framework