Package publish automation

[raulfdm]

Hi everyone.

Since I was add as collaborator, I'd propose some changes to improve this library quality.
In a couple days I'll create more proposals and pull requests but this one is about automating the deployment process.

Proposal

My idea here is to use semantic-release to do this process for us.

For those who doesn't know what's this about, semantic release takes care of our versioning using Angular commit message versioning:

It means each commit made needs to follow this structure because it'll be used to:

1. decide what version would be next. If a commit with fix prefix is merged into master, then semantic release will automatically bump from 2.2.1 to 2.2.2 (minor version) for example;
2. Auto generates Change log when it happens;
3. Auto generates tag publish;

Needs

To set this flow only the only thing I need is a NPM_TOKEN environment variable to publish to npm and a GH_TOKEN to publish change logs and tags:

The rest is on me :)