Fixed apk download as zip bug on Firefox

mod/compatibility/browser.go

@@ -50,6 +50,8 @@ func BrowserCompatibilityOverrideContentType(userAgent string, filename string,
 			//Handle issue #105 for .ai file downloaded as .pdf on Firefox
 			//https://github.com/tobychui/arozos/issues/105
 			return "application/ai"
+		} else if filepath.Ext(filename) == ".apk" {
+			return "application/apk"
 		}
 	}
 	return contentType