Added box config to build phar files
feature #19 Added box config to build phar files (pgodel)

This PR was squashed before being merged into the 1.0-dev branch (closes #19).

Discussion
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Added box config to build phar files

With the box.json config file, you can easily create the phar file with http://box-project.org/

Once box is installed, just run box build from the directory of the symfony-installer. Make sure you ran composer install before.

Commits
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86bf3d3 Added box config to build phar files