chore: set up semantic-release

[fernandoespinosa]

These changes and the execution of semantic-release were tested as follows:

1. A temporary release branch named release-branch in the forked repo was used as the source of releases. However this PR makes master the final release branch.

   • This branch was made protected and updated though the regular process of Pull Request on GitHub.
   • These PRs contained simple changes with conventional-commit messages as enforced by commitlint (see previous chore: set up conventional-commits #1).

2. Sample link to PR included in a release: feat/feature 3 fernandoespinosa/polymath-sdk#5

3. The actual semantic-release was triggered upon PR merge onto the release-branch from a temporary local CI environment (TeamCity running on Docker).

4. The actual publishing was made to the temporary testing npm account fernando.polymath.network

5. The final effects of the successful release look like this:
   

[RafaelVidaurre]

Looking good! the next step would be then to setup travis to do this, right?

[RafaelVidaurre]

Also, it seems like we will want to have beta releases as well on a next branch.

[fernandoespinosa]

@RafaelVidaurre - exactly, next step will be to configure the CI build/release process. I will also look into beta releases and a next branch...

[fernandoespinosa]

🎉 This PR is included in version 1.0.0 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot 📦🚀