fix reading encrypted frames that don't line up with network frames

[ccutrer]

we want to call step again if there's remaining data. pos + toWrite
is what we consumed from this network frame to complete the encrypted
frame. so if it's less than the total network frame (data.length),
then call step again.

[timcharper]

@beowulfe any chance you can grant me reviewing powers ? I'd like to give this a +1

[andylintner]

Thanks @ccutrer - this is a great fix! Could be the cause of a quite a few odd issues!

@timcharper - looks like I can't give granular permissions on a personal repo. But Inacknowledge your +1 :)

[timcharper]

I'm really rather wondering if the window covering bug was triggered with this! And removing the other characteristics caused it to stop triggering it.

It was failing in fantastic ways. Such a great fix!!!

@beowulfe do you feel like we're ready for a new point release? I'd like to start merging my openhab changes and integrating into master.

[ccutrer]

I'd like to get ccutrer@1544779 (or some variation thereof) merged before a new point release. It was far easier to remove the LowBatteryStatusAccessory rather than trying to keep it compatible-but-deprecated. See #70.

[timcharper]

I'll move the discussion there :)