Update .gitignore to ignore OS X specific hidden file
Update .gitignore to ignore OS X specific hidden file

jan-zajic/mesos-hdfs,dmitrypekar/hdfs,jmlvanre/hdfs,mesosphere/hdfs,ryane/hdfs,smorin/hdfs,ryane/hdfs,dmitrypekar/hdfs,kensipe/hdfs,kensipe/hdfs,mesosphere/hdfs,jan-zajic/mesos-hdfs,jmlvanre/hdfs,smorin/hdfs