Update repository command

[g4s8]

Add update repository command to apply new changes to repository or create new one.
This command takes mandatory --file or -f parameter with repository config, see: https://github.com/artipie/artipie/wiki/Configuration-Repository. And it takes mandatory repository key (it's just repository name for flat layout, e.g. mydocker; or org+name for org layout, e.g. artipie/mydocker).

API docs: https://github.com/artipie/maven-adapter/
Ticket: #2

[orlovm]

At the moment artipie doesn't provide necessary api endpoints.
Waiting for a solution to the issue artipie/artipie#972