Refactor and document update settings methods

Just continued to refactor and document the methods responsible for
updating the settings in the client and main activity.

Signed-off-by: Konrad Reiche <konrad.reiche@gmail.com>
Glue restore state and download snapshot together

With this commit I have decided again to glue two protocol actions
together. The restore client state action and the download snapshot
action.

With this change I have also started to create methods in the client
controller for sending messages to the handler in order to purge the
code further and separate the responsibilities.

Signed-off-by: Konrad Reiche <konrad.reiche@gmail.com>