Install fresh debian and update your package using https://www.dotdeb.org/instructions/
apt-get install redis-server
sudo apt-get install python g++ make bzip2 libpcre3-dev libssl-dev daemon libgeoip-dev libcurl4-gnutls-dev libexpat1-dev gettext libz-dev libssl-dev build-essential curl
Install some package before installing ruby
apt-get install make sudo
cd /tmp/
wget http://cache.ruby-lang.org/pub/ruby/2.1/ruby-2.1.6.tar.gz
tar xvzf ruby-2.1.6.tar.gz
./configure
make
make install
gem install bundle
gem install slanger