Move \OCP to PSR-4

lib/public/IConfig.php

lib/public/IContainer.php

lib/public/IDBConnection.php

lib/public/IDateTimeFormatter.php

lib/public/IDateTimeZone.php

lib/public/IDb.php

lib/public/IEventSource.php

lib/public/IGroup.php

lib/public/IGroupManager.php

lib/public/IHelper.php

lib/public/IImage.php

lib/public/IL10N.php

lib/public/ILogger.php

lib/public/IMemcache.php

lib/public/IMemcacheTTL.php

lib/public/INavigationManager.php

lib/public/IPreview.php

lib/public/IRequest.php

lib/public/ISearch.php

lib/public/ISession.php