Hwchiu/add travis

[hwchiu]

• Add the travis support
• Add the codecov support
• Add the testing for OVS fuunction
• Add the badge in README

[codecov-io]

Codecov Report

❗ No coverage uploaded for pull request base (master@e0a807d). Click here to learn what that means.
The diff coverage is n/a.

@@          Coverage Diff           @@
##             master    #1   +/-   ##
======================================
  Coverage          ?   20%           
======================================
  Files             ?     1           
  Lines             ?    15           
  Branches          ?     0           
======================================
  Hits              ?     3           
  Misses            ?    11           
  Partials          ?     1

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