Install Ruby, Compass and Sass with RBENV and Bundle on Ubuntu 14.04

First Uninstall ruby and gem from your current setup so we have no conflicts

sudo apt-get purge ruby rubygems

Next install the Personal Package Archives (PPA)  for Node.js

sudo apt-add-repository -y ppa:chris-lea/node.js

Install python properties

sudo apt-get install python-software-properties

Now we update 

sudo apt-get -y update

And install node.js, git-core and Curl

sudo apt-get -y install curl git-core nodejs

We can now use Curl to download RBENV from git

curl | bash

Now update .bashrc to set your path to RBENV by adding this to the top of .bashrc in your home folder

export RBENV_ROOT="${HOME}/.rbenv"
if [ -d "${RBENV_ROOT}" ]; then
  export PATH="${RBENV_ROOT}/bin:${PATH}"
  eval "$(rbenv init -)"
Restart bashrc

source ~/.bashrc

Install missing dependencies

rbenv bootstrap-ubuntu-12-04

List ruby versions and install the latest

rbenv install --list
rbenv install 2.3.0
(rbenv rehash) This is now deprecated as added to rbenv core as off version 0.1.2
When finished make this version of ruby default by setting it to global

rbenv global 2.3.0

Now we are nearly there, just need to install bundler which does most of the work for you setting up the config file with a list of required gems for each project and install the right gems per project

gem install bundler

Now we are ready, if you project has a gem file just navigate to that directory and run

bundle install

If you are starting you own project just run bundle init from within the project directory and add you gems to the gem file it creates

bundle ini

If you need a different ruby version for any local project we can tell RBENV to create a local ruby version for this project by running this in your project folder

rbenv local 2.3.0