Update installation docs to reduce the amount of possible errors

Closes #2080
Fixes #2264

doc/install/installation.md

@@ -32,15 +32,24 @@ The GitLab installation consists of setting up th following components:
 # 1. Packages / Dependencies
-*Keep in mind that `sudo` is not installed on Debian by default. You should install it as root:*
-    apt-get update && apt-get upgrade && apt-get install sudo
+`sudo` is not installed on Debian by default. If you don't have it you'll need
+to install it first.
+    # run as root
+    apt-get update && apt-get upgrade && apt-get install sudo vim
 Make sure your system is up-to-date:
     sudo apt-get update
     sudo apt-get upgrade
+**Note:**
+Vim is an editor that is used here whenever there are files that need to be
+edited by hand. But, you can use any editor you like instead.
+
+    # Install vim
+    sudo apt-get install -y vim
+
 Install the required packages:
     sudo apt-get install -y wget curl build-essential checkinstall libxml2-dev libxslt-dev libcurl4-openssl-dev libreadline6-dev libc6-dev libssl-dev zlib1g-dev libicu-dev redis-server openssh-server git-core libyaml-dev postfix
@@ -65,6 +74,8 @@ Make sure you have the right version of Python installed.
 # 2. Ruby
+Download and compile it:
+
     wget http://ftp.ruby-lang.org/pub/ruby/1.9/ruby-1.9.3-p327.tar.gz
     tar xfvz ruby-1.9.3-p327.tar.gz
     cd ruby-1.9.3-p327
@@ -72,6 +83,10 @@ Make sure you have the right version of Python installed.
     make
     sudo make install
+Install the Bundler Gem:
+
+    sudo gem install bundler
+
 # 3. System Users
@@ -101,6 +116,7 @@ Create a user for GitLab:
 Clone GitLab's fork of the Gitolite source code:
+    cd /home/git
     sudo -u git -H git clone -b gl-v304 https://github.com/gitlabhq/gitolite.git /home/git/gitolite
 Setup Gitolite with GitLab as its admin:
@@ -109,16 +125,15 @@ Setup Gitolite with GitLab as its admin:
 GitLab assumes *full and unshared* control over this Gitolite installation.
     # Add Gitolite scripts to $PATH
-    cd /home/git
-    sudo -u git -H mkdir bin
-    sudo -u git -H sh -c 'echo -e "PATH=\$PATH:/home/git/bin\nexport PATH" >> /home/git/.profile'
+    sudo -u git -H mkdir /home/git/bin
+    sudo -u git -H sh -c 'printf "%b\n%b\n" "PATH=\$PATH:/home/git/bin" "export PATH" >> /home/git/.profile'
     sudo -u git -H sh -c 'gitolite/install -ln /home/git/bin'
     # Copy the gitlab user's (public) SSH key ...
     sudo cp /home/gitlab/.ssh/id_rsa.pub /home/git/gitlab.pub
     sudo chmod 0444 /home/git/gitlab.pub
-    # ... and use it as the Gitolite admin key for setup
+    # ... and use it as the admin key for the Gitolite setup
     sudo -u git -H sh -c "PATH=/home/git/bin:$PATH; gitolite setup -pk /home/git/gitlab.pub"
 Fix the directory permissions for the repository:
@@ -183,7 +198,6 @@ Make sure to edit both files to match your setup.
     cd /home/gitlab/gitlab
     sudo gem install charlock_holmes --version '0.6.9'
-    sudo gem install bundler
     sudo -u gitlab -H bundle install --deployment --without development test 
 ## Configure Git