Gzip encoded calendar urls fail to load

[ubertao]

Platform: Raspberry Pi 3B+, Electron 2.0.0

Node Version: v9.11.2

MagicMirror Version: v2.4.1

Description:
Some calendar servers (e.g. icloud.com) responses are gzip encoded, calendar module won't load them.

Steps to Reproduce:
Add "https://p33-calendars.icloud.com/holidays/cn_zh.ics" to calendar module.
(Or any url which response is gzip encoded.)

Expected Results:
Calendar module displays the calendar events.

Actual Results:
Calendar always displays "loading".

Configuration:

{
    module: "calendar",
    header: "China Holidays",
    position: "top_left",
    config: {
        calendars: [
            {
                symbol: "calendar-check-o ",
                url: "https://p33-calendars.icloud.com/holidays/cn_zh.ics"
            }
        ]
    }
}

[MichMich]

Fix merged.