Changes in editing team

Hi all,

unfortunately both Adam Bergqvist and Taylor Brandstetter have told us 
that they will not be able to continue in their Editor roles for 
mediacapture-main and webrtc-pc due to moving on to other work.

For Adam this is effective immediately, while Taylor will continue until 
the end of the month (June).

Luckily Henrik Boström (Google) has agreed to join the Editors team, 
starting immediately.

We'd like to thank both Adam and Taylor for all their hard work (a quick 
look at the commit history shows how many contributions they have made 
over the years) and welcome Henrik!

Stefan for the chairs