Class rename, composer add, phpUnit tests add

Rename the class from ReadEnvFile to DotEnv.
Add everything to a composer json file so it can be published to
composer repository.
Add phpUnit tests for system

vendor/composer/autoload_files.php

@@ -0,0 +1,11 @@
+<?php
+
+// autoload_files.php @generated by Composer
+
+$vendorDir = dirname(dirname(__FILE__));
+$baseDir = dirname($vendorDir);
+
+return array(
+    'ec07570ca5a812141189b1fa81503674' => $vendorDir . '/phpunit/phpunit/src/Framework/Assert/Functions.php',
+    '6124b4c8570aa390c21fafd04a26c69f' => $vendorDir . '/myclabs/deep-copy/src/DeepCopy/deep_copy.php',
+);