Update upstream API change LoadRemote to LookupRemote.
Update upstream API change LoadRemote to LookupRemote.

See libgit2/git2go@1d759e3697#diff-8e6330727d1d48f71afe77830d9f9adeL321.
alexsaveliev/go-vcs,alexsaveliev/go-vcs,pombredanne/go-vcs,pombredanne/go-vcs