moving config.js into app/

config.js should be in the app folder because it concerns the app and
nothing else
Improving tester.js

tester.js move from client/node_modules to client/js
tester.js is auto loaded in when config.debug is true
client/tests is read recursively to include subfolder
adding a window.testModule method to write tests for a specific module
easyly
improved tester.js code for a better logging on failed tests