breakup-984365: Add delayed loading to api.js
breakup-984365: Add delayed loading to api.js

addItemsByModule now allows custom loaders, and there is a load function
to perform delayed load actions.

Signed-off-by: Joe Walker <7a17872fbb32c7d760c9a16ee3076daead11efcf@mozilla.com>

joewalker/gcli,mozilla/gcli,mozilla/gcli,mozilla/gcli,joewalker/gcli