updating to alpine 3.9 & adding psutil prereqs

Author: Naor Livne

Dockerfile

@@ -1,10 +1,11 @@
 # it's offical so i'm using it + alpine so damn small
-FROM python:2.7.15-alpine3.8
+FROM python:2.7.15-alpine3.9
 
 # copy the codebase
 COPY . /worker
 
-# install required packages
+# install required packages - requires build-base due to psutil GCC complier requirements
+RUN apk add --no-cache build-base python2-dev linux-headers
 RUN pip install -r /worker/requirements.txt
 
 #set python to be unbuffered