Adding Florian to the MobileFrontend author list

Now that Florian has passed 100 merged commits to MobeilFrontend,
it's probably about time to add him as an official author of the
extension.

Thanks for your all your tireless volunteer work on mobile, Florian!
It is greatly appreciated! Hope we get to meet in person one of these
days.

Change-Id: I6285bd9a661de1d4080b265b63df4fe1a1b05da3
Merge "Adding Florian to the MobileFrontend author list"