support native reads and writes into S3

[romange]

we currently can read only from a local file system. It could be nice if we could read natively from s3.
Also we should consider to support https://github.com/minio/minio (could probably help with e2e tests locally as well).
(I am not sure what does it mean to support min.io since they should be compatible with S3 API)

we already have a POC code here: https://github.com/romange/gaia/tree/master/util/aws
but it will require changes to be adopted into helio - better abstractions, better reliability, no check-fails, use helio sockets etc.

[romange]

https://github.com/romange/gaia/blob/master/file/s3_file.h file can serve as an example of how it can be done

[romange]

Update: s3_demo works.
./s3_demo lists all buckets
./s3_demo --path s3://bucket/prefix will list files under the bucket
./s3_demo --cmd read s3://bucket/obj_path will output first K bytes of the file. If the bucket is located in a different region - error is returned.

[romange]

docker run --rm    -p 9000:9000    -p 9090:9090    --user $(id -u):$(id -g)    --name minio1    -e "MINIO_ROOT_USER=root"    -e "MINIO_ROOT_PASSWORD=12345678" -v ${HOME}/minio/config:/root/.minio   -v ${HOME}/minio/data:/data    quay.io/minio/minio server /data  --console-address ":9090"

and then export AWS_ACCESS_KEY_ID=root and export AWS_SECRET_ACCESS_KEY=12345678

[romange]

we do not get etag sometimes.

1.log

[andydunstall]

As agreed with Ari - assigning myself to work on cloud snapshots (added a separate 'cloud snapshots' project which breaks this issue up a bit)

[romange]

Thanks Andy!
Please note this PR in progress - #133 which will remove icu/xml2 shared library dependencies from our binaries.

[andydunstall]

I think this can be closed now given cloud snapshots were added in last release