add codecov to travis and repo

[r2d4]

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[codecov-io]

Codecov Report

❗ No coverage uploaded for pull request base (master@53bbca8). Click here to learn what that means.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master     #885   +/-   ##
=========================================
  Coverage          ?   37.48%           
=========================================
  Files             ?       54           
  Lines             ?     2521           
  Branches          ?        0           
=========================================
  Hits              ?      945           
  Misses            ?     1465           
  Partials          ?      111

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