add a docker setup to do linux builds of the RDKit code

docker-build/Dockerfile

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+FROM centos:centos6
+MAINTAINER Greg Landrum <greg.landrum@t5informatics.com>
+
+ARG anaconda_token
+ARG anaconda_user
+
+RUN yum update -y && yum install -y \
+  wget \
+  gcc-c++ \
+  git \
+  cairo \
+  libXext \
+  patch \
+  cmake
+
+# conda
+RUN echo 'export PATH=/opt/conda/bin:$PATH' > /etc/profile.d/conda.sh && \
+    wget --quiet https://repo.continuum.io/miniconda/Miniconda3-4.3.11-Linux-x86_64.sh && \
+    /bin/bash /Miniconda3-4.3.11-Linux-x86_64.sh -b -p /opt/conda && \
+    rm Miniconda3-4.3.11-Linux-x86_64.sh
+
+ENV PATH /opt/conda/bin:$PATH
+ENV LANG C
+
+# actually do the conda install
+RUN conda config --prepend channels  https://conda.anaconda.org/rdkit
+RUN conda config --append channels  https://conda.anaconda.org/conda-forge
+RUN conda install -y nomkl numpy=1.13 boost=1.56 eigen conda-build=2.1.17 anaconda-client
+
+
+RUN mkdir /src
+WORKDIR /src
+RUN git clone https://github.com/rdkit/conda-rdkit
+WORKDIR /src/conda-rdkit
+RUN git checkout development
+
+RUN \
+    conda build nox --quiet --no-anaconda-upload && \
+    conda build cairo_nox --quiet --no-anaconda-upload && \
+    CONDA_PY=35 conda build rdkit --quiet --user=$anaconda_user --token=$anaconda_token && \
+    CONDA_PY=36 conda build rdkit --quiet --user=$anaconda_user --token=$anaconda_token && \
+    CONDA_PY=27 conda build rdkit --quiet --user=$anaconda_user --token=$anaconda_token

docker-build/README.md

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+Dockerfile for doing RDKit linux builds and uploading the results to conda.
+
+Note that you need to provide a conda user and conda token for this to work. Example invocation:
+```
+docker build -t conda-docker-build --build-arg anaconda_user=rdkit --build-arg anaconda_token="REPLACE_ME" .
+```