Update and rename 2013-10-12-wheel-building-class.md to 2013-10-15-wheel-building-class.md
Merge pull request #15 from bikepit/wheel-building

Wheel building
Merge pull request #17 from bikepit/master

Clarify that wheel building class is free.
Delete 2013-10-12-wheel-building-class.md
Update 2013-10-15-wheel-building-class.md
Merge pull request #18 from bikepit/gh-pages

Fix my mistakes :)