Meta server: use "-c" option to create empty file system only, report an error and exist if checkpoint file already exists, exit immediately after creating empty file system, do not start servicing requests. The primary intention of this change is to make it harder to unintentionally destroy an existing file system.
Test scripts: change end to end, endurance, and recovery tests to explicitly create an empty file system by specifying -c when required.
Examples: change sample setup to explicitly create an empty file system by using -c option.
Annotated configuration files: add comment to the meta server configuration file to use -c option to create an empty file system.