updated readme with installation, usage, requirements, documentation …

…and tests examples

README.md

@@ -1,4 +1,38 @@
-rebilly-php
+Installation
 ===========
+*  You can copy the files into your project.
+*  You can clone this repository if you use git.
+*  If you use composer, you can install from composer as well.
 
-https://www.rebilly.com php client library
+Usage
+==========
+Include `rebilly_api.php`, set the environment, set your api key, and then use according to documentation.
+```php
+require('./client/php/rebilly_api.php');
+
+$customer = new RebillyCustomer();
+$customer->setEnvironment(RebillyRequest::ENV_SANDBOX);
+$customer->setApiKey(API_SECRET_KEY);
+```
+
+Requirements
+==========
+* PHP 5.3+ (tested with 5.3, 5.4, 5.5)
+* CURL
+* Codeception (tests only)
+
+Documentation
+===========
+Read https://www.rebilly.com/api/documentation for more details.
+
+Tests
+===========
+* Install codeception (recommended install with Composer).
+
+```bash
+#  install required files
+composer install
+
+#  run the tests (from project root)
+./vendor/codeception/codeception/codecept run
+```