RileyLinkKit: Provide a connection log

[loudnate]

Was trying to help someone diagnose connection errors, turns out the BLE device was constantly connecting and disconnecting. It would be nice to keep a ring buffer of things we're currently NSLog-ing and display them in a view controller with the option to share the contents.

@ps2 do you have any strong feelings about how this should behave? I was thinking of keeping the buffer on the RileyLinkKit side and surfacing a delegate method in BLEKit.

[ps2]

That sounds good.

[loudnate]

My theory on the connection failures, btw, is the G4 Share App / Receiver.