Import cities warnings

[llybin]

Geonames db contain duplictaes of cities
cities_light has unique key ('region', 'name')
In summary we have integrity errors on saving.

For checking, one of many, can find in cities1000.txt "Bykovo"

570298  Bykovo  Bykovo  Bykovo,Быково   55.63614        38.08027        P       PPL     RU              47                              10700           136     Europe/Moscow   2014-06-30
570300  Bykovo  Bykovo  Bykovo,Быково   55.62075        38.0797 P       PPL     RU              47                              1721            133     Europe/Moscow   2014-07-08

force_insert and force_update were taken out of TRY for static analisator.

[codecov]

Codecov Report

Merging #187 into master will increase coverage by 0.02%.
The diff coverage is 82.35%.

@@            Coverage Diff             @@
##           master     #187      +/-   ##
==========================================
+ Coverage   94.29%   94.31%   +0.02%     
==========================================
  Files          25       25              
  Lines        1402     1407       +5     
==========================================
+ Hits         1322     1327       +5     
  Misses         80       80

Impacted Files	Coverage Δ
cities_light/management/commands/cities_light.py	87.46% <82.35%> (+0.18%)	⬆️

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