Cleanups

Clean up most unfinised things, typoes, compile errors, etc. Still won't
compile due to address change from uint8[6] to char *, which is addressed by
the next commit.
BlueTooth addresses are strings now
Small tty poll fixup

Don't make the expiry timer run twice as fast and avoid needless tty name
string format.
Keep the RFCOMM tty fd open, so that MM won't keep reconnecting

See: https://bugzilla.gnome.org/show_bug.cgi?id=736984

For Bluez4 the bluetoothd does this as we call Connect via DBus.

NB: Despite it's not wise anyway, there's a bug in the kernel that deferred
rfcomm tty teardown races with the new open. The newly open tty gets a HUP
which confuses NM and the deallocation fails on a refcount check, making the
old rfcomm stuck in the kernel, needing a reboot for another reopen to succeed.
Add some debug logs

In case the errors ommit the diagnostic information, it's useful to have them
in logs.

Remove dun_find_channel

Fold it into nm_bluez5_dun_connect. We alway go find the channel once the
connection is initiated.
c2
Finally fix call back into bt device

Hopefully success as well as all error conditions are covered.