Added: Commands "jobmeta" and "stats"

[starrify]

Resolves #276

[codecov-io]

Codecov Report

Merging #277 into master will increase coverage by 0.08%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #277      +/-   ##
==========================================
+ Coverage   91.36%   91.45%   +0.08%     
==========================================
  Files          30       32       +2     
  Lines        1957     1977      +20     
==========================================
+ Hits         1788     1808      +20     
  Misses        169      169

Impacted Files	Coverage Δ
shub/tool.py	95% <ø> (ø)	⬆️
shub/jobmeta.py	100% <100%> (ø)
shub/stats.py	100% <100%> (ø)

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[jdemaeyer]

Hi Pengyu, thanks a lot for this PR. :)

I had refrained from merging this so far because I would like to unify all the job-related commands under a shub job umbrella, hosting these two new commands as well as items, log, and requests.

However, now I think we should just get this out there and then work on the shub job umbrella for the next major release. Code LGTM, are there any last-minute concerns that riped over the last months from you? ;)