[feature] Media buttons on headsets

[WhyNotHugo]

When pressing play/next/etc buttons on headsets, Daedalus doesn't react.

It'd be really useful to able to play/pause, etc using headset buttons, to avoid having to take the phone out of the pocket and unlock it.

[fph]

Support has been added with commit 537a55. The version on the Jolla store has not been updated yet, so you have to compile from source. In addition, if you have a Jolla C (bluez5 broken in 2.1.1), you may need to apply also the suggestion here to get it to work.