[libcontacts] Resolve unknown addresses after unsuccesful resolve

If an initial resolution attempt is not successful, test new addresses
for potential resolution.
Merge pull request #25 from matthewvogt/resolve-unknown

[libcontacts] Resolve unknown addresses after unsuccesful resolve
[libcontacts] Add a grouping property configuration

Allow grouping policy to be configured independently from sorting
and display label order.
Merge pull request #26 from matthewvogt/group-property

[libcontacts] Add a grouping property configuration
Increment pkgconfig version to match tag