Merge branch 'abs' of git://github.com/nc6/aura into abs

Conflicts:
	Aura/AUR.hs
Started `The Great Abstraction`
ABS module (probably) complete

- Decided to go with `ABSPkg` over `PkgInfo` to be more consistent.
- Three critical functions: absSync, repository, and absPkg are done.
`Buildable` abstractions confirmed - Aura compiles
Started work on a common backend for `A` and `M`
Merge changes from upstream/abs

Some modifications:
- Lift 'buildable' to 'package' method on 'Package'.
- Export 'absSync', do not sync automatically on package lookup.
- Use directory structure rather than pacman for finding stuff
  in the ABS tree. This admittedly feels messy!