conversationmodel: remove temp/pending convs after adding
conversationmodel: remove temp/pending convs after adding

When converting a temporary or invite into a permanent conversation
adding the new conversation first will make it simpler to reselect
the right conversation by keeping the to-be-removed conv data until
the conversationReady signal has treated.

Change-Id: Ibd8abaa9b7b7769853fc25a83bda495391581c89

savoirfairelinux/ring-lrc,savoirfairelinux/ring-lrc,savoirfairelinux/ring-lrc,savoirfairelinux/ring-lrc,savoirfairelinux/ring-lrc