Bumping the Guile version requirement

[Ludovic Courtès]

address@hidden (Ludovic Courtès) skribis:

> You should be able to get compilation going with the patch below, but
> getting the HTTP client to work with 2.0.5 will require more work.

I think for 0.8.2 I will actually bump the requirement to Guile 2.0.7 or
2.0.9 (the latter is what Debian 8 has.)  People on older systems will
still be able to install Guix using the binary tarball.

What do people think?

Ludo’.