New installer script, fixed templates, fixed bugs/typos and updated icon (fixes #350)

Summary of changes:

* There is a completely new fail-proof (hopefully) installer script, that installs all the templates and required libraries for v3 preview.
* All the templates have been edited, validated and formatted to work properly (and be pretty-looking)
* Improved the organization of the templates added new directories to sort things better
* Changed ObjectiveChipmunk to be added as a fat static lib in templates, to fix issues with non-ARC code
* Fixed a few bugs and typos in order to make the templates compile
* Updated README.md with new information and removed old links/titles
* Added completely new iOS7-ready icon

This pull request fixes issue #350.