Added Gemfile and updated Readme.md for rubygems based installation of vagrant

Gemfile

+source 'https://rubygems.org'
+gem 'vagrant'
\ No newline at end of file

Gemfile.lock

+GEM
+  remote: https://rubygems.org/
+  specs:
+    archive-tar-minitar (0.5.2)
+    childprocess (0.3.9)
+      ffi (~> 1.0, >= 1.0.11)
+    erubis (2.7.0)
+    ffi (1.6.0)
+    i18n (0.6.4)
+    json (1.7.7)
+    log4r (1.1.10)
+    net-scp (1.0.4)
+      net-ssh (>= 1.99.1)
+    net-ssh (2.2.2)
+    vagrant (1.0.7)
+      archive-tar-minitar (= 0.5.2)
+      childprocess (~> 0.3.1)
+      erubis (~> 2.7.0)
+      i18n (~> 0.6.0)
+      json (>= 1.5.1, < 1.8.0)
+      log4r (~> 1.1.9)
+      net-scp (~> 1.0.4)
+      net-ssh (~> 2.2.2)
+
+PLATFORMS
+  ruby
+
+DEPENDENCIES
+  vagrant

Readme.md

@@ -12,25 +12,28 @@ Currently we _automagically_ install the build dependencies for the following pr
 
 ## To start building
 
-* Install vagrant, see http://docs.vagrantup.com/v1/docs/getting-started/index.html for more information.
-* Clone this project!
+* Install vagrant, see http://docs.vagrantup.com/v1/docs/getting-started/index.html for more information. (Or install the latest version by running the following command)
+  ```bash
+  bundle install
   ```
+* Clone this project!
+  ```bash
   git clone https://gitlab.eox.at/vagrant/builder_rpm.git ./
   ```
 * Edit the _Vagrantfile_ and update the project (see the beginning of [Vagrantfile](/vagrant/builder_rpm/tree/master/Vagrantfile))
 * Copy your source archive into the _build/SOURCES_ folder
 * Copy your spec file into the _build/SPECS_ folder 
 * Start the VM
-  ```
+  ```bash
   vagrant up
   ```
 * Open a SSH connection
-  ```
+  ```bash
   vagrant ssh
   ```
 * Change to the rpmbuild folder
 * Build your RPMs
-  ```
+  ```bash
   rpmbuild -ba SPECS/project.spec
   ```
 * Wait ...