Update Ceph FSAL configuration to match others.

* better error returns and diagnostics
* add some configuration stubs
* cosmetic: reformatting, comments

There are some ceph functions here that are not present in any release
version of ceph.  This marks them "if 0" for future work.  This isn't
useful without pnfs / ds, which this code doesn't (yet) support.

Revise the configuration logic to better match the pattern used
in all the other fsals.  No more silly cases in fs_supports()!

Also: create files, symlinks, and directories with the permissions
actually requested, and support "fs_umask" to reduce those permissions
like the other fsals do.

Signed-off-by: William Allen Simpson <bill@cohortfs.com>
Signed-off-by: Marcus Watts <mdw@cohortfs.com>