add a gitignore file to ignore cache and dependency manager files
add a gitignore file to ignore cache and dependency manager files

flodolo/webdashboard,flodolo/webdashboard,mozilla-l10n/webdashboard,pascalchevrel/webdashboard,mozilla-l10n/webdashboard,flodolo/webdashboard,mozilla-l10n/webdashboard,pascalchevrel/webdashboard