pypyPackages.lxml: 3.0.2 -> 3.3.6 (fixes pypy build)
pypyPackages.psycopg2: disable
pypyPackages.pycurl: disable
ack: update from 2.12 to 2.14
blueman: update from 1.21 to 1.23
buildPythonPackage: support .override {}
pythonPackages.sqlalchemy{,8}: disable on py34
memtest86: update from 4.3.3 to 4.3.6
mysql55: update from 5.5.37 to 5.5.39, potentially fixes CVE-2014-2494, CVE-2014-4207, CVE-2014-4258, CVE-2014-4260
mysql: update from 5.1.72 to 5.1.73, potentially fixes CVE-2013-5908, CVE-2014-0401, CVE-2014-0412, CVE-2014-0437
python34Packages.httplib2: update from 0.8 to 0.9, potentially fixes CVE-2013-2037
Merge pull request #3899 from aristidb/dhcpcd-systemd

start dhcpcd after network-interfaces
shared_mime_info: update from 1.2 to 1.3
at: update from 3.1.14 to 3.1.15
atd: use /var/setuid-wrappers/sendmail by default instead of ssmtp
pcre: update from 8.34 to 8.35
nixos-option: fixes as suggested by @nbp
lua-5.2: minor update to fix CVE-2014-5461

Note that almost all packages use lua-5.1 which does remain vulnerable,
as they released no update on that branch. CC: @peti.
telegram-cli: work around a build problem
Initial configuration + image generation script for Micro$oft Azure. Work in progress for #3986.