travis: build only on node 8 for now (node 4 and 6 failing on MacOSX)
travis: build only on node 8 for now (node 4 and 6 failing on MacOSX)

mvertes/node-parquet,skale-me/node-parquet,skale-me/node-parquet,mvertes/node-parquet,mvertes/node-parquet,skale-me/node-parquet,skale-me/node-parquet,mvertes/node-parquet