Update library current + age (ie libs are now 3.1.0)

Update library current + age (ie libs are now 3.1.0)

- We haven't removed or changed any interfaces in a way that would
  require full soname bump, only a handful of new interfaces have
  been added.
- There aren't actually any new interfaces in librpmbuild or librpmsign
  but for sanity and consistency's sake they're all updated...