add singularity files for macs2

src/singularity_modules/macs2/2.1.2/macs2.def

+Bootstrap: docker
+From: ubuntu:18.04
+%labels
+MAINTAINER Laurent Modolo
+%post
+
+MACS_VERSION=2.1.2
+PACKAGES="git \
+build-essential \
+python-pip \
+ca-certificates \
+python-setuptools \
+python-dev \
+python-numpy \
+python-wheel \
+zlib1g-dev"
+
+apt-get update && \
+apt-get install -y --no-install-recommends ${PACKAGES} && \
+apt-get clean
+
+pip install MACS2==${MACS_VERSION}
+
+%environment
+export MACS_VERSION=2.1.1.20160309
+
+%runscript
+exec /bin/bash "$@"