Create zipball / tarball feature

Archives are cached in cache/archives/repo/tree to never generate
the same tree archive twice.

controllers/archiveController.php

@@ -0,0 +1,32 @@
+<?php
+
+use Symfony\Component\HttpFoundation\StreamedResponse;
+
+$app->get('{repo}/{format}ball/{branch}', function($repo, $format, $branch) use($app) {
+    $repository = $app['git']->getRepository($app['git.repos'] . $repo);
+    $tree = $repository->getBranchTree($branch);
+
+    if (false === $tree) {
+        return $app->abort(404, 'Invalid commit or tree reference: '.$branch);
+    }
+
+    $file = $app['cache.archives'].DIRECTORY_SEPARATOR.$repo.DIRECTORY_SEPARATOR.substr($tree, 0, 2).DIRECTORY_SEPARATOR.substr($tree, 2).'.'.$format;
+
+    if (!file_exists($file)) {
+        $repository->createArchive($tree, $file, $format);
+    }
+
+    return new StreamedResponse(function () use($file) {
+        readfile($file);
+    }, 200, array(
+        'Content-type' => ('zip' === $format) ? 'application/zip' : 'application/x-tar',
+        'Content-Description' => 'File Transfer',
+        'Content-Disposition' => 'attachment; filename="'.$repo.'-'.substr($tree, 0, 6).'.'.$format.'"',
+        'Content-Transfer-Encoding' => 'binary',
+        'Content-Length' => filesize($file),
+    ));
+})->assert('format', '(zip|tar)')
+  ->assert('repo', '[\w-._]+')
+  ->assert('branch', '[\w-._]+')
+  ->value('format', 'zip')
+  ->bind('archive');