This PR also does backend format change to 1.0.1
from 1.0.0. Backward compatible changes are still
kept to read the 'md5Sum' key. But all new objects
will be stored with the same details under 'etag'.
Fixes#4312
- Due to usage of amazon SDK, spark expects md5sum of empty string to be
returned when it does PUT on a directory.
- The fix returns md5sum of a empty string for the above mentioned case.
- This fixes the issue of Apache Spark not being able to write into Minio.
Make sure to skip reserved bucket names in `ListBuckets()`
current code didn't skip this properly and also generalize
this behavior for both XL and FS.
This is a consolidation effort, avoiding usage
of naked strings in codebase. Whenever possible
use constants which can be repurposed elsewhere.
This also fixes `goconst ./...` reported issues.
