OCS API for server-to-server sharing

apps/files_sharing/api/local.php

apps/files_sharing/api/server2server.php

apps/files_sharing/appinfo/app.php

apps/files_sharing/appinfo/database.xml

apps/files_sharing/appinfo/routes.php

apps/files_sharing/appinfo/version

apps/files_sharing/lib/activity.php

apps/files_sharing/lib/external/manager.php

apps/files_sharing/lib/helper.php

apps/files_sharing/tests/api.php

apps/files_sharing/tests/server2server.php

lib/private/share/share.php

lib/public/share.php

ocs/routes.php