Minor fixes

[ricardobranco777]

Minor fixes:

• Use pylint on more files and fix issues that appeared.
• Avoid dangerous-default-value.
• Avoid re where unneeded.

[codecov]

Codecov Report

Patch coverage: 61.11% and project coverage change: +0.07 🎉

Comparison is base (7bfb361) 77.74% compared to head (bba29a5) 77.82%.

❗ Current head bba29a5 differs from pull request most recent head 370c0ee. Consider uploading reports for the commit 370c0ee to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #277      +/-   ##
==========================================
+ Coverage   77.74%   77.82%   +0.07%     
==========================================
  Files          20       20              
  Lines        1456     1461       +5     
==========================================
+ Hits         1132     1137       +5     
  Misses        324      324              

Impacted Files	Coverage Δ
ocw/enums.py	68.75% <0.00%> (ø)
ocw/lib/db.py	53.03% <ø> (ø)
ocw/lib/openstack.py	77.10% <ø> (ø)
ocw/models.py	71.87% <50.00%> (ø)
ocw/views.py	57.14% <50.00%> (+1.04%)	⬆️
ocw/tables.py	70.88% <66.66%> (+1.14%)	⬆️
ocw/apps.py	75.00% <100.00%> (ø)
webui/PCWConfig.py	100.00% <100.00%> (ø)
webui/settings.py	92.10% <100.00%> (-0.21%)	⬇️

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