Building Arrow-Parquet integration

To use Arrow C++ with Parquet, you must first build the Arrow C++ libraries and install them someplace. Then, you can build parquet-cpp with the Arrow adapter library:

# Set this to your preferred install location
export ARROW_HOME=$HOME/local

git clone https://github.com/apache/parquet-cpp.git
cd parquet-cpp
cmake -DCMAKE_INSTALL_PREFIX=$PARQUET_HOME
make -j4
make install