Add .DS_Store to .gitignore
Add .DS_Store to .gitignore

.DS_Store is generated by OS X

Change-Id: I1be71f35fe8c5ccdda46ff7ee49c65fd1925b48c

hongbin/magnum,hongbin/magnum,eshijia/magnum,sajuptpm/magnum,jay-lau/magnum,Alzon/SUR,ffantast/magnum,paulczar/magnum,ramielrowe/magnum,eshijia/SUR,ArchiFleKs/magnum,mjbrewer/testindex,mjbrewer/testindex,sajuptpm/magnum,dimtruck/magnum,dimtruck/magnum,mjbrewer/testindex,ddepaoli3/magnum,LaynePeng/magnum,Tennyson53/SUR,eshijia/magnum,ffantast/magnum,openstack/magnum,ChengTiesheng/magnum,Tennyson53/magnum,openstack/magnum,eshijia/SUR,annegentle/magnum,ddepaoli3/magnum,ChengTiesheng/magnum,LaynePeng/magnum,Tennyson53/SUR,Alzon/SUR,annegentle/magnum,Tennyson53/magnum,ArchiFleKs/magnum,ramielrowe/magnum,paulczar/magnum