Elgg/Elgg — pull request #6733 by juho-jaakkola (2014-04-16 13:54:22+00:00)
Title: perf(upgrade): ajaxifies data directory migration

This allows upgrade.php to complete more quickly by moving the user data directory migrations to a separate page with an ajax process.

Fixes #6202
Replaces #6336

Changes to Steve's original PR:
- Uses the generic XHR upgrade view and js
- Uses the ElggUpgrade object
- Fixes a bug that made it upgrade only the first ten users
- Rebased with latest master