Pygit2 0.22.0 released, updates to libgit2 0.22.0

This release requires the recently released libgit2 0.22.0; other changes include an improved support for remotes. See the full list of changes.

Thanks to Carlos Martín Nieto, Matthew Duggan, Greg Fitzgerald, Kevin Kin-Foo, Richard Möhn, Lukas Fleischer, Peter Dave Hello and Philippe Ombredanne.