This commit fixes the Manta gateway client creation flow. We now affix
the endpoint scheme with endpoint URL while creating the Manta client
for gateway.
Also add steps in Manta gateway docs on how to run with custom Manta
endpoint.
Fixes#6408
To pass a custom S3 endpoint in S3 gateway, the user needs
to specify it as an argument after 'minio gateway s3' and not
as '--address' option since this latter specifies the address
to which the gateway should listen.
Manta has the ability to allow users to authenticate with a
username other than the main account. We want to expose
this functionality to minio manta gateway.
Manta is an Object Storage by [Joyent](https://www.joyent.com/)
This PR adds initial support for Manta. It is intended as non-production
ready so that feedback can be obtained.
With https://github.com/minio/minio/pull/4869 maximum size of a single
multipart upload part in not restricted to 100MB. 1TB maximum object
size limitation is no longer applicable too.
