Extra Sidebar Widgets: Upcoming Events renders new lines as "n" characters

In the Upcoming Events widget, new lines are shown as "n" instead of becoming br tags.

I'm using Google Calendar's ICS links in my widget and I have hit this particular scenario.

If your calendar app created an event with a location like this:

School
Happy Avenue 201
Lima

It will be exported in an ICS as:

```
LOCATION:School\nHappy Avenue 201\nLima
```

It will be shown in the sidebar widget as:
SchoolnHappy Avenue 201nLima

It seems this is because the code uses stripslashes() instead of stripcslashes():
https://github.com/Automattic/jetpack/blob/master/_inc/lib/icalendar-reader.php#L730

I believe the solution would be to change that, and then convert the new lines to br tags, or blank spaces.

Start at _inc/lib/icalendar-reader.php around line 730 and trace how the escaped LOCATION value reaches the Upcoming Events widget. Reproduce the supplied ICS location and verify that its line breaks render as breaks or spaces rather than literal "n" characters.

Written by the indexing model from the issue text.