Improve formatting of punch from notification

[tupaschoal]

#55 introduced punching from notification, but it emits a message that is "[H]?H:[m]?m", so these are a few examples on what looks like and what it should look like for different times:

• 8:8 -> 08:08
• 8:11 -> 08:11
• 10:8 -> 10:08

[ozgunbal]

I'm on it.

[thamara]

Thanks @ozgunbal !