FileHandler returns incorrect MIME type if extension has capital letters

[sanand0]

FileHandler checks file extensions to get the MIME type. But this fails if the extension has capital letters. For example:

>>> mimetypes.types_map.get('.jpg')
'image/jpeg'
>>> mimetypes.types_map.get('.JPG')
None

Impact: .JPG files are served as text.

Solution:

• Replace self.file.suffix with self.file.suffix.lower()
• Add test cases to check the MIME type in test_filehandler.py

[pratapvardhan]

closed via a96d729