Publish blog post about Grid List

We have a first draft https://docs.google.com/a/ubervu.com/document/d/1WmqqPWHNTMa22yQ1q0WFjONwtkBOV0sZS7zL84jX4qI/edit

Need to:
- [x] finalise it
- [x] put it in markdown and put it in the GitHub pages blog
- [ ] publish it
- [ ] tell everybody so we can share it

We also need to promote it (see https://github.com/uberVU/blog/issues/7)