Add Changelog for new release

[lucaong]

List changes between release 2.10.0 and upcoming release (assuming it will be named 2.11.0), as discussed here: #372 (comment)

Notes:

1. There were 3 successive commits dealing with the Bunny dependency: bump 2.9.2 to 2.10.0, bump to 2.11.x and, finally, bump and loosen dependency to ~> 2.12. I choose to mention only the last one, as it supersedes the previous two. I did mention the contributors though.
2. Non-functional changes (docs improvement, code style) are included in one summary, mentioning the contributors: even though they do not affect the functionality, so they do not require a detailed description in the changelog, these contributions do deserve credit
3. I did not bump up the Sneakers version, as this should be done by maintainers upon releasing, and I assumed the new release will be called 2.11.0. I think it's the appropriate version number, but if this changes the heading in the changelog must also be changed

Thanks everybody for the great work, hoping to see the new release in Rubygems soon :)

[lucaong]

@gabrieljoelc is this PR helping you publishing a new release on Rubygems?

Given that the commits included in this release add one backward-compatible feature (support for :bind_arguments option), I think the semver release number should be 2.11.0.

[gabrieljoelc]

@lucaong yes, this was so helpful. thank you! I will try to get doing the releases some time this week or next.

[gabrieljoelc]

ugh, been super busy and didn't get to this. sorry! going to shoot for getting this done before 2019 😬

[gabrieljoelc]

@lucaong thank you so much for getting this done. It is finally pushed to rubygems. Sorry for the delay.

I also added a release and copied in these changelog changes

[lucaong]

You're welcome, thanks a lot for publishing the release!