Drop support for Debian Lenny, Ubuntu Hardy, RHEL 5, CentOS 5

[Dan Scott]

These distributions are no longer supported by the distribution community itself (Debian Lenny), or really old, and require many packages to be installed from source or backports, along with extra backflips and handstands. In comparison, new releases like Fedora 16 / 17 and Ubuntu 12.04 simply require packages. Glorious!

Therefore, drop support for the crufty old distros from the README and Makefile.install for the 2.1.0 release.

Accordingly, find the following branches in the working repo:

* user/dbs/README_distros (master)
* user/dbs/README_distros_2_1 (rel_2_1)

I've successfully installed from these branches on totally clean Debian Squeeze and Fedora 17 minimal images (with one minor addition to the package list--tar--required due to a perplexing autotools puzzle). And the Makefile.install is remarkably cleaner...

[Dan Scott (denials)]

Tested with Ubuntu Precise successfully as well.