Return empty hash from list if directory doesn't exist.

Conflicts:

	test/list.test.js

lib/mbtiles.js

@@ -76,6 +76,7 @@ MBTiles.registerProtocols = function(tilelive) {
 MBTiles.list = function(filepath, callback) {
     filepath = path.resolve(filepath);
     fs.readdir(filepath, function(err, files) {
+        if (err && err.code === 'ENOENT') return callback(null, {});
         if (err) return callback(err);
         for (var result = {}, i = 0; i < files.length; i++) {
             var name = files[i].match(/^([\w-]+)\.mbtiles$/);

test/list.test.js

@@ -15,14 +15,9 @@ exports['list'] = function(beforeExit, assert) {
     var completed = false; beforeExit(function() { assert.ok(completed); });
 
     MBTiles.list(fixtures.doesnotexist, function(err, list) {
-        assert.ok(err);
-        assert.ok(err.code.match(/^ENOENT/));
-        
-        MBTiles.list(fixtures.doesnotexist, function(err, list) {
-            completed = true;
-            assert.ok(err);
-            assert.ok(err.code.match(/^ENOENT/));
-        });
+        completed = true;
+        assert.equal(err, null);
+        assert.deepEqual(list, {});
     });
 };