Upgraded astroid to 0.8 and uses the upstream changes to properly
propagate environment without a patch. Note that this still uses an
unsupported version of webkitgtk and thus will fail to build, but if
allow webkitgtk to install, astroid will run.
Astroid was unable to run in a pure environment because it couldn't find
the necessary icons. This fixes that issue, and was tested with
`nix-shell --pure`
