remove python3 install

Author: Max Burnette

sample-extractors/simple-extractor/Dockerfile

@@ -1,11 +1,11 @@
+ARG PYCLOWDER_PYTHON=""
+FROM clowder/pyclowder${PYCLOWDER_PYTHON}:latest
 
 ENV EXTRACTION_FUNC=""
 ENV EXTRACTION_MODULE=""
 
 COPY simple_extractor.py .
 
-RUN apt-get update && apt-get install -y build-essential python3-dev
-
 # install any packages
 ONBUILD COPY packages.* Dockerfile /home/clowder/
 ONBUILD RUN if [ -e packages.apt ]; then \