Fixed test break and JSON MIME type. Fixes issue #2978.

framework/helpers/mimeTypes.php

@@ -71,6 +71,8 @@ return [
     'jpeg' => 'image/jpeg',
     'jpg' => 'image/jpeg',
     'js' => 'application/x-javascript',
+	'json' => 'application/json',
+	'jsonp' => 'text/javascript',
     'kar' => 'audio/midi',
     'latex' => 'application/x-latex',
     'lha' => 'application/octet-stream',

tests/unit/framework/helpers/FileHelperTest.php

@@ -348,10 +348,14 @@ class FileHelperTest extends TestCase
         $file = $this->testFilePath . DIRECTORY_SEPARATOR . 'mime_type_test.txt';
         file_put_contents($file, 'some text');
         $this->assertEquals('text/plain', FileHelper::getMimeType($file));
-
+		
+		// see http://stackoverflow.com/questions/477816/what-is-the-correct-json-content-type
+		// JSON/JSONP should not use text/plain - see http://jibbering.com/blog/?p=514
+		// with "fileinfo" extension enabled, returned MIME is not quite correctly "text/plain"
+		// without "fileinfo" it falls back to getMimeTypeByExtension() and returns application/json
         $file = $this->testFilePath . DIRECTORY_SEPARATOR . 'mime_type_test.json';
         file_put_contents($file, '{"a": "b"}');
-        $this->assertEquals('text/plain', FileHelper::getMimeType($file));
+        $this->assertTrue(in_array(FileHelper::getMimeType($file), array('application/json', 'text/plain')));
     }
 
     public function testNormalizePath()