fixed up paragraphs 1 and 2
Added caveat about engine version (closes #4)
Moved content around a bit
Merge pull request #16 from marcoscaceres/setup

Changes to setup file...
moved chapter title back to top
Reviewed devtools.md

Note that I added some details about the limitations of the simulator.
I also added stuff about why using alert is bad.
Fixed typos
Merge branch 'devtools' of https://github.com/marcoscaceres/firefoxos-quick-guide into devtools