changes concerning dataset contact form (+captcha) and developers page

[smanousopoulos]

installed following packages for wheezy.captcha to work:

apt-get install libjpeg libjpeg-dev libfreetype6 libfreetype6-dev zlib1g-dev

as seen here http://askubuntu.com/questions/156484/how-do-i-install-python-imaging-library-pil