support: update external tarballs

This patch updates our internal copy of flake8, pyflakes and pep8 to:

    flake8==2.1
    pep8==1.5.1
    pyflakes==0.8.1

Fixes: https://bugs.launchpad.net/checkbox/+bug/1299006

Signed-off-by: Zygmunt Krynicki <zygmunt.krynicki@canonical.com>
"automatic merge by tarmac [r=sylvain-pineau][bug=][author=zkrynicki]"
checkbox-old: remove launchpad exports

Signed-off-by: Zygmunt Krynicki <zygmunt.krynicki@canonical.com>
"automatic merge by tarmac [r=zkrynicki][bug=][author=zkrynicki]"
support: use /etc/os-release or emulate it if needed

This patch moves away from lsb_release(1) in favour of the
/etc/os-release file. The latter is now the de-facto standard on all
distributions and provides additional meta-data we can use.

The code is adjusted to fill in the missing data from lsb_release on
12.04.1 or earlier that didn't yet use os-release.

Signed-off-by: Zygmunt Krynicki <zygmunt.krynicki@canonical.com>
support: add partial Fedora support

This patch marks Fedora 19 and 20 as partially supported, adds a new
support script (install-rpm-dependencies), makes both
install-deb-dependencies and install-ppa-dependencies gracefully exit if
dpkg is not installed and lastly adds requirements/rpm-*.txt files that
capture most of the content of their requirements/deb-*.txt
counterparts.

Signed-off-by: Zygmunt Krynicki <zygmunt.krynicki@canonical.com>
support: update support IRC channel name

Signed-off-by: Zygmunt Krynicki <zygmunt.krynicki@canonical.com>
support: require basic i18n packages

Signed-off-by: Zygmunt Krynicki <zygmunt.krynicki@canonical.com>