[INTERNAL] gitignore: added .DS_Store to gitignore
[INTERNAL] gitignore: added .DS_Store to gitignore

Change-Id: I3b2415fdb539576b2ed52b6af7a4ce3c16ac9ddb

SQCLabs/openui5,SAP/openui5,cschuff/openui5,SAP/openui5,olirogers/openui5,SQCLabs/openui5,nzamani/openui5,SAP/openui5,nzamani/openui5,SQCLabs/openui5,SAP/openui5,nzamani/openui5,cschuff/openui5,cschuff/openui5,olirogers/openui5,olirogers/openui5