Bug#797340: choose-mirror: use httpredir.debian.org by default

[Michael Gilbert <mgilbert@debian.org>]

package: choose-mirror
severity: wishlist
version: 2.65

This article [0] had some extensive complaints about Debian, one of
which is that the installer has too many screens (apparently 20 in
their case).

Setting a default mirror without user intervention would nicely save 3
of those steps, and httpredir.debian.org is in many ways the ideal
mirror selection anyway.

Obviously expert mode would want to retain the full 3 screen mirror
selection process.

Best wishes,
Mike

[0]http://www.everydaylinuxuser.com/2015/06/3-ways-to-improve-debian-and-i-havent.html