Patches: Bail out when failure in ABS download, build or customizepkg.

Here are two patches that make `yaourt` bail out if

* `customizepkg` fails,
* download `PKGBUILD` from ABS fails,
* installation from ABS fails.

`abs.abort-on-error.patch`::http://ix.io/1l0y
`yaourt_customizepkg-abort-on-error.patch`::http://ix.io/1l0z

Please incorporate such changes.
