repo: Make the body parameter to ostree_repo_commit optional
repo: Make the body parameter to ostree_repo_commit optional

https://bugzilla.gnome.org/show_bug.cgi?id=707727

gatispaeglis/ostree,leandrosansilva/ostree,resin-io/ostree,sujitfulse/ostree,GNOME/ostree,leandrosansilva/ostree,resin-io/ostree,sujitfulse/ostree,gatispaeglis/ostree,resin-io/ostree,sujitfulse/ostree,sujitfulse/ostree,leandrosansilva/ostree,resin-io/ostree,leandrosansilva/ostree,GNOME/ostree,gatispaeglis/ostree,gatispaeglis/ostree,leandrosansilva/ostree,GNOME/ostree,gatispaeglis/ostree,sujitfulse/ostree,resin-io/ostree,gatispaeglis/ostree,GNOME/ostree,GNOME/ostree