Bug 841251 - Implement a simple shared lazy loader.

https://bugzilla.mozilla.org/show_bug.cgi?id=841251

This centralizes the work done by the lazy loader into a single shared file. This is basically the same implementation that @mozsquib has done - just centralized.

App work is done for Email, Calendar, Gallery. TODO: Contacts, Dialer, Everything.me apps, more..