Update to use PSR-4 autoloading

Author: clue

composer.json

@@ -36,7 +36,10 @@
         "react/event-loop": "You need some kind of event loop for this to make sense."
     },
     "autoload": {
-        "psr-0": { "React\\Async": "src" }
+        "psr-4": { "React\\Async\\": "src/" }
+    },
+    "autoload-dev": {
+        "psr-4": { "React\\Tests\\Async\\": "tests/" }
     },
     "extra": {
         "branch-alias": {

phpunit.xml.dist

@@ -9,11 +9,11 @@
          processIsolation="false"
          stopOnFailure="false"
          syntaxCheck="false"
-         bootstrap="tests/bootstrap.php"
+         bootstrap="vendor/autoload.php"
 >
     <testsuites>
         <testsuite name="React-Async Test Suite">
-            <directory>./tests/React/</directory>
+            <directory>./tests/</directory>
         </testsuite>
     </testsuites>