Ray uses env vars to determinate build flavors. Figure out the right parameters

• SKIP_THIRDPARTY_INSTALL=1 to skip pip install psutil setproctitle colorama in setup.py?
• BUILD_JAVA=0 to disable Java builds?
• RAY_INSTALL_CPP ?
• work around Bazel's sandbox by making ccache diretory writable: BAZEL_ARG="--sandbox_writable_path=/path/to/ccache"