modified talk, moved to core and changed it to callouts

[lauramillan]

No description provided.

[eric-brechemier]

@lauramillan I fixed a small issue in your last commit, removing hidden file .DS_Store. I also added a .gitignore file at the root of the repository to prevent the issue in the future.
https://github.com/eric-brechemier/oocss/tree/gitignore

You may merge this fix from the command line:
$ git remote add eric git://github.com/eric-brechemier/oocss.git
$ git pull eric gitignore

[stubbornella]

I think we need to change the classnames to match the new file names (and also the documentation). They should all refer to "callout" rather than "bubble".