VOL-1449 Modify build environment to use pyvoltha

Depending on if LOCAL_PYVOLTHA is set use a build of
the library from the nearby source tree, for both
virtualenv and docker image builds.  By default
requirements.txt uses the pip hosted dev build, which
may not be new enough for iterative development

Also by setting PYVOLTHA_BASE_IMAGE use a docker image produced
by pyvoltha as the base image.

Change-Id: Ibf7218b92450f92d6a3f1c9d837be46fcc3a84db
diff --git a/python/docker/Dockerfile.base b/python/docker/Dockerfile.base
index 1b912e0..898f7fa 100644
--- a/python/docker/Dockerfile.base
+++ b/python/docker/Dockerfile.base
@@ -18,17 +18,13 @@
 
 # Update to have latest images
 RUN apt-get update && \
-    apt-get install -y python python-pip openssl iproute2 libpcap-dev wget
+    apt-get install -y python openssl iproute2 libpcap-dev wget build-essential git binutils python-dev libffi-dev libssl-dev 
 
+# Install current version of pip rather than outdated pip from apt
+RUN wget -O /tmp/get-pip.py https://bootstrap.pypa.io/get-pip.py
+RUN python /tmp/get-pip.py
+
+# Install adapter requirements. 
 COPY requirements.txt /tmp/requirements.txt
+RUN pip install -r /tmp/requirements.txt
 
-# pip install cython enum34 six && \
-# Install app dependencies
-RUN wget https://github.com/Yelp/dumb-init/releases/download/v1.2.0/dumb-init_1.2.0_amd64.deb && \
-    dpkg -i *.deb && \
-    rm -f *.deb && \
-    apt-get update && \
-    apt-get install -y wget build-essential make gcc binutils python-dev libffi-dev libssl-dev git && \
-    pip install -r /tmp/requirements.txt && \
-    apt-get purge -y wget build-essential make gcc binutils python-dev libffi-dev libssl-dev git && \
-    apt-get autoremove -y