Make it possible for rws to work with any repository topology

[LeonidVas]

Now rws is adapted to work with the tarantool repositories topology on S3.
Necessary to

• Implement the ability to set an arbitrary repository topology in config (take into account gpg binding to repositories)
• implement work with repositories located on different buckets

Config should be implemented in such a way that will allow to specify a set of repositories using templates.
For example: I don't want to list all 600+ tarantool repositories manually, now the repository topology is specified by some kind of "schema" in JSON.