As Signal Desktop does not allow its users to update the contact names,
it would be nice to be able to update contact names from signal-cli when
the latter is the master device.
The command `setContactName` allow to set the name for the given contact
in the local store. `sendContacts` can then be used to push the updated
contact list on Signal servers.
Closes#228
Two new commands are added `setProfileName` and `setProfileAvatar` which
allow to update the name and avatar visible by other users for the
current profiles.
Closes#227
