[#256] Add sematic-release to package.json

[thedaviddias]

Fixes: #256

• Check the commit's or even all commits' message styles matches our requested structure.
• Check your code additions will fail neither code linting checks nor unit test.

Short description of what this resolves:

Using semantic-release will automatically change the version number without any possible interpretation.

Proposed changes:

• Add semantic-release node package
• Update travis.yml to automatically launch semantic-release if all tests pass

👍 Thank you!

[codecov-io]

Codecov Report

❗ No coverage uploaded for pull request base (master@22174ac). Click here to learn what that means.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             master   #257   +/-   ##
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  Coverage          ?   100%           
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  Files             ?      2           
  Lines             ?      2           
  Branches          ?      1           
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  Hits              ?      2           
  Misses            ?      0           
  Partials          ?      0

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