todos leftover from #18

[unkcpz]

Since #18 is quite large and contains major changes about tests and CLI, I get it merged first and move todos for separated small PRs:

• [ ] If remote binary exist, cannot override install. Hit sftp error (OSError: Failure)
• [x] Think of is it a new problem after eiger updated, only from the same login node can access the server.
• [ ] Specifying HQ_SERVER_DIR explicitly, to distinguish multiple server (see https://github.com/It4innovations/hyperqueue/issues/719)
• [ ] Implementing CLI ports to pause and resume the alloc.