workflow: always upload REANA specification on create and restart

[audrium]

closes #623

[codecov-commenter]

Codecov Report

Merging #647 (22245c4) into master (6f0657d) will increase coverage by 1.06%.
The diff coverage is 12.90%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #647      +/-   ##
==========================================
+ Coverage   56.65%   57.71%   +1.06%     
==========================================
  Files          22       24       +2     
  Lines        2203     2327     +124     
==========================================
+ Hits         1248     1343      +95     
- Misses        955      984      +29     

Impacted Files	Coverage Δ
reana_client/cli/workflow.py	63.03% <12.90%> (+0.08%)	⬆️
reana_client/__init__.py	100.00% <0.00%> (ø)
reana_client/utils.py	75.86% <0.00%> (ø)