Add Composer packaging

 composer.json

New file
@@ -0,0 +1,13 @@
{
    "name": "jacekkow/uphpcas",
    "type": "library",
    "description": "Simple PHP library for CAS authentication",
    "homepage": "https://github.com/jacekkow/uphpcas",
    "license": "BSD-3-Clause",
    "require": {
        "php": ">=5.3.0"
    },
    "autoload": {
        "classmap": ["uphpCAS.php"]
    }
}