[contactsd] Store account and provider display names on contacts

Requires https://github.com/nemomobile/telepathy-accounts-signon/pull/10

Store the account and provider display names from Telepathy in new fields of QContactOnlineAccount. That gives UI everything it needs for a good presentation of accounts without dipping into libaccounts or telepathy.

In the current implementation, these fields are added on all accounts, both self and remote. That should be okay as long as we're properly avoiding unnecessary changes after the startup sync.

So, we're doing extra changes after the startup sync. Currently, the storage info arrives later than the rest of the account info, and results in a second set of contact updates at startup. I will try to resolve that in another commit before merging, so consider this a pre-review.