Added installation script for OS X dependencies under tools/ (#80)

* consolidated OS X instructions to the shell script, removed step-by-step instructions from README.md

README.md

@@ -89,21 +89,11 @@ There is also a demo application:
 
 ## Build on Mac OS X
 
-The following instructions were verified with Mac OS X El Capitan.
+Run the [install_osx_dependencies.sh](./tools/install_osx_dependencies.sh)
+script in the `tools/` directory. The script installs dependencies
+via [Homebrew](http://brew.sh) and then downloads and installs the TensorFlow
+library on your machine under `/usr/local`.
 
-- Install dependencies via [Homebrew](http://brew.sh):
+After running the script to install system dependencies, build the project with stack: 
 
-        brew install protobuf
-        brew install snappy
-
-- Install the TensorFlow library on your machine:
-
-        curl https://storage.googleapis.com/tensorflow/libtensorflow/libtensorflow-cpu-darwin-x86_64-1.0.0.tar.gz > libtensorflow.tar.gz
-        tar zxf libtensorflow.tar.gz -C /usr/local
-        mv /usr/local/lib/libtensorflow.so /usr/local/lib/libtensorflow.dylib
-        install_name_tool -id libtensorflow.dylib /usr/local/lib/libtensorflow.dylib
-        rm libtensorflow.tar.gz
-
-- Run stack:
-
-        stack test
+    stack test

tools/install_osx_dependencies.sh

@@ -0,0 +1,41 @@
+#!/bin/bash
+set -eu
+
+echo "Installing OSX System Dependencies"
+echo "=================================="
+
+if ! type "brew" > /dev/null; then
+    echo "Requires homebrew to be installed."
+    echo "Install homebrew from https://brew.sh/"
+    exit 1
+fi
+
+if brew ls --versions protobuf > /dev/null; then
+    echo "protobuf installation detected."
+else
+    echo "protobuf not installed, installing with homebrew."
+    brew install protobuf
+fi
+
+if brew ls --versions snappy > /dev/null; then
+    echo "snappy installation detected."
+else
+    echo "snappy not installed, installing with homebrew."
+    brew install snappy
+fi
+
+echo "Downloading libtensorflow..."
+curl https://storage.googleapis.com/tensorflow/libtensorflow/libtensorflow-cpu-darwin-x86_64-1.0.0.tar.gz > libtensorflow.tar.gz
+
+echo "Extracting and copying libtensorflow..."
+tar zxf libtensorflow.tar.gz -C /usr/local
+rm libtensorflow.tar.gz
+mv /usr/local/lib/libtensorflow.so /usr/local/lib/libtensorflow.dylib
+
+sudo install_name_tool -id libtensorflow.dylib /usr/local/lib/libtensorflow.dylib
+
+echo "Installing submodule dependencies"
+git submodule update --init --recursive
+
+echo ""
+echo "Finished"