Add setup_env.sh and requirements.txt to install dependencies

Kudos to Julia Kreger, I shamelessly copied the setup_env.sh
script from her fantastic bifrost project.

requirements.txt

@@ -0,0 +1,3 @@
+shade
+shade-ansible
+jinja2

setup_env.sh

@@ -0,0 +1,53 @@
+#!/bin/bash
+set -e
+
+if [ -x '/usr/bin/apt-get' ]; then
+    if ! $(git --version &>/dev/null) ; then
+        sudo -H apt-get -y install git
+    fi
+    if ! $(pip -v &>/dev/null); then
+        sudo -H apt-get -y install python-pip
+    fi
+elif [ -x '/usr/bin/yum' ]; then
+    if ! $(git --version &>/dev/null); then
+        sudo -H yum -y install git
+    fi
+    if ! $(pip -v &>/dev/null); then
+        sudo -H yum -y install python-pip
+    fi
+else
+    echo "ERROR: Supported package manager not found.  Supported: apt,yum"
+fi
+
+sudo -E pip install -r "$(dirname $0)/requirements.txt"
+
+u=$(whoami)
+g=$(groups | awk '{print $1}')
+
+if [ ! -d /opt/stack ]; then
+    mkdir -p /opt/stack || (sudo mkdir -p /opt/stack)
+fi
+sudo -H chown -R $u:$g /opt/stack
+cd /opt/stack
+
+if [ ! -d ansible ]; then
+    git clone https://github.com/ansible/ansible.git --recursive
+else
+    cd ansible
+    git checkout devel
+    git pull --rebase
+    git submodule update --init --recursive
+    git fetch
+    # Temporary direct checkout of devel due to broken modules until
+    # the submodules pointers get updated in the core ansible repo.
+    cd lib/ansible/modules/core
+    git checkout devel
+fi
+
+echo
+echo "If your using this script directly, execute the"
+echo "following commands to update your shell."
+echo
+echo "source env-vars"
+echo "source /opt/stack/ansible/hacking/env-setup"
+echo