Guillaume Roguez authored Jun 20, 2017 and Adrien Béraud committed Jun 22, 2017

upnp is always activated even if no account uses it.

Here we refactoring its creation and availability checks.
This also removes an atomic_bool that gives no true conccurent
protection as it protects itself, but not multiple accesses
to upnp_ member.

Change-Id: Ibf6aaee54077867cdf3029fd51ef6cae0b7488c1