ENH: Add ANTsPy analog for Faces example

[dzenanz]

However, the result is not as good:

[ntustison]

Thanks. I'm pretty sure this repository was put together before ANTsPy and I'm certain it was before Richard Beare added quite a bit to the build_template functionality. However, not all the parameters are exposed, and for this particular face case, the unexposed shrink and smoothing factors are pretty important. The shell analog parameters differ significantly from the default.