Finalized Jupyterlab for the sprint

Dockerfile

-FROM jupyter/scipy-notebook:hub-1.5.0
+FROM jupyter/datascience-notebook:hub-3.1.1
 
 # Install from APT repository
 USER root
 RUN apt-get update -y
-RUN apt-get install -y git libpq-dev gcc
-
-# Set working directory
-WORKDIR /usr/src/app
+RUN apt-get install -y git
 
 # Install basics
 USER jovyan
 RUN pip3 install --upgrade pip
 
-# Install python packages
+# RUN pip3 install --upgrade pip
+RUN pip install jupyter-server-proxy==4.0.0
+RUN pip install jupyterlab-git==0.42.0
+RUN pip install jupyterlab-gitlab==3.0.0
+
 COPY requirements.txt requirements.txt
 RUN pip install --no-cache-dir -r requirements.txt