[ofono] first connect interfaces, then process

Signed-off-by: Denis Zalevskiy <denis.zalevskiy@jolla.com>
[ofono] process sim presence separately

sim presence is tri-state, sometimes it is impossible to exactly
report is sim present or no (ofono crash/restart, modem power down
etc.), this is now reflected by separate property
Sim ("present"/"absent/"" - not a boolean to allow to extend this
property with additional values). Contextkit property
RegistrationStatus has the same behaviour as before ("no-sim" state if
sim presence is unknown).

Signed-off-by: Denis Zalevskiy <denis.zalevskiy@jolla.com>
Merge pull request #20 from nemomobile/sim-presence

Processing sim presence separately