Update README.md

Added the requirement of pip for Vagrant users in readme.
See issue #2766

README.md

@@ -34,7 +34,10 @@ To deploy the cluster you can use :
 
 ### Vagrant
 
-    # Simply running `vagrant up` (for tests purposes)
+    Check if Python and pip are installed: python -v && pip -v
+    If this returns the version of the software you're good to go if not download and install Python from here https://www.python.org/downloads/source/
+    Install the necessary requirements
+    sudo pip install -r requirements.txt
     vagrant up
 
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