Add namespace tag when dumping cloud stat

[asmorodskyi]

From the beginning we querying over all namespaces defined for PCW.
But currently we saving everything together no matter from which namespace
measurement have come. This does not make sense we should add tag which will
allow to distinguish one namespace from another

[codecov]

Codecov Report

Attention: Patch coverage is 60.00000% with 2 lines in your changes are missing coverage. Please review.

Project coverage is 78.50%. Comparing base (0c55a03) to head (4f7f774).
Report is 3 commits behind head on master.

Files	Patch %	Lines
ocw/lib/influx.py	60.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #360      +/-   ##
==========================================
+ Coverage   78.48%   78.50%   +0.02%     
==========================================
  Files          22       22              
  Lines        1668     1669       +1     
==========================================
+ Hits         1309     1310       +1     
  Misses        359      359              

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