Add some Content-Types

image/bmp: Windows bitmap (*.bmp), unofficial, IANA unregistered, Microsoft's de facto standard.
image/jpg: JPEG (*.jpg), unofficial, IANA unregistered, some MUA's typo, registered type is image/jpeg.
image/vnd.microsoft.icon: Windows icon (*.ico), IANA registered.
Merge pull request #47 from trueroad/patch-4

Add some Content-Types