reorganzied/renamed folder structure to follow ofxAddonTemplate, generated projects

Changes:

* reorganzied/renamed folder structure to follow ofxAddonTemplate
* ofxBox2d now works with the OF ProjectGenerator
* generated project files for OSX, Win VS, and Linux CB
* updated readme, gitignore, and install.xml

Also, I found your commits which coincided with version updates (0062-007, 007-0071) and tagged them. There is info in the readme so people know to get a tag if they are using an older version of OF. All you have to do is make a new tag when you are updating for a new OF version in the future.

I don't think this will be part of the Pull Request, so you can tag them manually:

* 007: a578ccfb2439812df3e73c7b6963aa2ac6c4cbb6
* 0062: 793635fe0fe23415e5dddade6755d69431ddb353

I did it like this:

<pre>
git checkout 793635fe0fe23415e5dddade6755d69431ddb353
git tag 0062
git checkout a578ccfb2439812df3e73c7b6963aa2ac6c4cbb6
git tag 007
git checkout master
git push --tags  
</pre>