[Outlook] DTSTART and DTEND values missing colon

The attached patch provides the missing colons for the Outlook display. I also had to update the test logic a bit to correctly pull the $entity->label() value for the mock. Not sure when that went sideways, but the change should be pretty uncontroversial.

I tested that patch and confirmed it worked! Thank you so much!

Based on the comment above, I'm setting this to RTBC.

I think this might justify a timely new beta release (1.1.0-beta2) that includes this change, since all MS Outlook imports are currently nonfunctional in 1.1.0-beta1.

Since this has been RTBC'd -- and I reviewed this again just now and feel good about it -- I'll merge it into 1.1.x-dev, noting that the only functional change is the addition of the colon; the rest is fixing test logic.

Automatically closed - issue fixed for 2 weeks with no activity.