Converted component to a controlled version

[StanleySathler]

This PR convert the component's code to a controlled version, according to the request on #6. However it is still being discussed.

[willianjusten]

I didn't tested properly yet, but it would be nice to add tests to check the states and see if it works normally.

[StanleySathler]

You're definitely right. I'll be providing them soon.

[StanleySathler]

@willianjusten I added a few specs in order to test checkbox's checked prop. Do you think is there any other way to make it even better?

Edit
Actually, it looks like CI thrown an issue regarding the defaultChecked removal. I'll check it further and update it properly.

[StanleySathler]

@willianjusten I've updated the missing unit tests. Also, an important note: I changed the old Git history for this Pull Request, so, if you have pulled it, just remove the local branch and pull it again. The Git history became really ugly while applying some updates.

[willianjusten]

I'll take a look tomorrow morning, please don't let me forget this.

[StanleySathler]

@willianjusten just reminding you again 😋

[willianjusten]

Just tested here, everything works, the code looks fine as well.
I'm not working with this component anymore, but I feel that this will be useful to more people =)

[willianjusten]

Release on 2.0.1