[libconnman-qt] Fix service list update.

Previously, the loop would just prepend the new services
to m_services, without removing old services, if num_old <= num_new.

Ie. old: [a,b,c] new: [c,d,e] would become [c,d,e,a,b]
Merge pull request #108 from mikkoharju/deletedservice

[libconnman-qt] Fix service list update.