net/seaweedfs: new port - distributed object store

SeaweedFS is a distributed object store and file system to store and
serve billions of files fast! Its object store has O(1) disk seek,
and transparent cloud integration. The Filer supports cross-cluster
active-active replication, POSIX, S3 API, encryption, Erasure Coding for
warm storage, FUSE mount, Hadoop, and WebDAV.

WWW: https://github.com/chrislusf/seaweedfs/wiki

Sponsored by: SkunkWerks, GmbH
Differential Revision: https://reviews.freebsd.org/D27391