Add instructions about creating a virtual enviroment and update dependencies auto-installer script (#16)

* Add instructions about prereq and dependency

* Add virtualenv dependency

README.md

@@ -1,2 +1,15 @@
 # vision-engine-layer-1
 Enviroment for the object recognition engine based on Google Cloud Vision
+
+## Dependencies
+To run the script you will need to install a few dependencies.
+First update your system using your favorite package manager, then run the script ./prerequisites.py to automatically install or update all the needed packages.
+You still need to have python and pip installed and updated.
+
+If you need to add new prerequisites, it is preferable to add them as a pip packages.
+
+## Prerequisites
+You will need to create a Python virtual enviroment for each enviroment folder in the repo, using:
+```bash
+    virtualenv ENVIROMENT-NAME
+```

dependencies.py

@@ -1,6 +1,7 @@
 import os
 
 # List of prerequisite packages needed
+os.system("pip install virtualenv")
 os.system("python -m pip install --upgrade pip")
 os.system("pip install numpy")
 os.system("pip install opencv-python")