fix issue not reporting complete list when supplying empty filter list

[kscheff]

Fix issue #68 not returning entire list when no filter for discovering services, characteristics

[CLAassistant]

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[philips77]

Hi, I don't understand. If servicesis empty, then

!services!.contains { ds in s.identifier == ds.identifier }

in

            let initialSize = services!.count
            services = services! + mockServices
                // Filter all device services that match given list (if set).
                .filter { serviceUUIDs?.contains($0.uuid) ?? true }
                // Filter those of them, that are not already in discovered services.
                .filter { s in !services!
                    .contains { ds in s.identifier == ds.identifier }
                  || initialSize == 0
                }
                ...

returns true...