GitHub Atom: How to apply a particular syntax highlighting to some files based on name

Question

How can I configure GitHub\'s Atom to make it automatically set a particular syntax highlighting to filenames based on name and/or extensions?

Specific

Answer 1

To add to Maurice Kelly's answer (my reputation is too low to comment) This is now documented at:

https://github.com/atom/flight-manual.atom.io/blob/681c7fe6e69f1f64396ecadfde1323a01e7f5b96/book/02-using-atom/sections/06-customizing.asc