Change PSR-0 to PSR-4

Add autoloading for testsuite from composer.

.gitignore

@@ -0,0 +1,3 @@
+/vendor
+/.idea
+composer.lock

composer.json

@@ -12,7 +12,10 @@
             "homepage": "http://erusev.com"
         }
     ],
+    "require-dev": {
+      "phpunit/phpunit": "~4.0"
+    },
     "autoload": {
-        "psr-0": {"Parsedown": ""}
+        "psr-4": {"": "src/"}
     }
 }

phpunit.xml.dist

@@ -1,5 +1,14 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<phpunit bootstrap="test/bootstrap.php" colors="true">
+<phpunit backupGlobals="false"
+         backupStaticAttributes="false"
+         bootstrap="vendor/autoload.php"
+         colors="true"
+         convertErrorsToExceptions="true"
+         convertNoticesToExceptions="true"
+         convertWarningsToExceptions="true"
+         processIsolation="false"
+         stopOnFailure="false"
+         syntaxCheck="false">
 	<testsuites>
 		<testsuite>
 			<file>test/ParsedownTest.php</file>

test/bootstrap.php

@@ -1,3 +0,0 @@
-<?php
-
-include 'Parsedown.php';