undefine "define" to avoid requirejs conflict
Don't show AJAX loader for preloaded panels.

Fix #582, #594. Thanks TacoDelPaco for the report and ionelmc for the fix.
Merge pull request #591 from mbarrien/jquery-require

undefine "define" to avoid requirejs conflict
Make the fix for #591 more focused and explain it.
Bump version number for 1.2.1.