Changes in Makefile
Add demo for Firefox OS

This is a modify version of the proof of concept for Firefox OS.

TODO:

* Add note in the documentation.
* Improve building.
* Fix bug when get element to process.
Some improves in the Firefox OS demo

* Improve the layout of the demo (adding gaia's headers).
* Some how the selection bug was fixed.
Add minimal examples to Firefox OS demo
Create a function to delete equations

The few lines that add a buttom to delete equations have been move
to a function and add a parameter that switch the buttom to be
visible or not (the case for the original equation).
Update documentation to cover Firefox OS demo
Fix problem in Makefile

The Makefile of Firefox OS have a little bug that have been fixed.