Add packages needed to build matplotlib after

Dockerfile

 from ubuntu:16.04
 
-# Install packages
+# Update apt-get packages
 RUN apt-get update &&\
-    apt-get -y upgrade &&\
-    apt-get install -y \
+    apt-get -y upgrade
+
+# Install required packages
+RUN apt-get install -y \
         pkg-config \
-        freetype* \
         wget \
-        python3-pip &&\
-    apt-get clean
+        libpng-dev # required to install matplotlib \
+        libjpeg8-dev # required to install matplotlib\
+        libfreetype6-dev # required to install matplotlib\
+        python3-pip
 
 # Update pip
 RUN pip3 install --upgrade pip