Bug 1090843 - Improve the time required for being interactive

- Delay load the modules for loading hardware information required in the module of the root panel.
- Delay the use of query selectors in the init function of the root panel.
- Remove redundant setTimeouts in the panel navigation process.
- Some modules required in main.js are delay loaded.
If by "the content" you mean the content that is displayed above-the-fold, then this event is fired to early according to bug 1079576 comments, 9, 11, 12. I also got confirmation from :Eli that this should be fired only after the screen stops updating (Airplane mode toggle switches, Wifi/Antenna status is displayed etc.)