Look for ".chirp_config" for Condor RemoteIO.

In HTCondor commit c584a30022712292294e823fa99173bfa2ff6049, HTCondor
accidentally renamed the file again to .chirp_config. This leaked into some
stable releases so we look for that filename too. HTCondor reverted the
filename change in 112d3b8ed85f78040acfb30ad47f52f944dae2f8.

Fixes #583.