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_psr4.php

@@ -0,0 +1,16 @@
+<?php
+
+// autoload_psr4.php @generated by Composer
+
+$vendorDir = dirname(dirname(__FILE__));
+$baseDir = dirname($vendorDir);
+
+return array(
+    'phpDocumentor\\Reflection\\' => array($vendorDir . '/phpdocumentor/reflection-common/src', $vendorDir . '/phpdocumentor/reflection-docblock/src', $vendorDir . '/phpdocumentor/type-resolver/src'),
+    'gullevek\\dotEnv\\' => array($baseDir . '/src'),
+    'Webmozart\\Assert\\' => array($vendorDir . '/webmozart/assert/src'),
+    'Prophecy\\' => array($vendorDir . '/phpspec/prophecy/src/Prophecy'),
+    'PhpParser\\' => array($vendorDir . '/nikic/php-parser/lib/PhpParser'),
+    'Doctrine\\Instantiator\\' => array($vendorDir . '/doctrine/instantiator/src/Doctrine/Instantiator'),
+    'DeepCopy\\' => array($vendorDir . '/myclabs/deep-copy/src/DeepCopy'),
+);