filesystems/py-tahoe-lafs: New port: Secure, decentralized, fault-tolerant file store

Tahoe-LAFS (Tahoe Least-Authority File Store) is the first free
software / open-source storage technology that distributes your
data across multiple servers. Even if some servers fail or are taken
over by an attacker, the entire file store continues to function
correctly, preserving your privacy and security.

PR:		287130
Approved by:	acm (mentor)