reset for 2014-08-25
I added a median function
Revert "I added a median function"

Reseting this to the state @gidden wanted for today's lesson.

This reverts commit b378e15007ba8ca5feaffb3f4a8b4374fac65084.
Fixing mean to behave correctly for floats.
The last change was redundant because it already worked for floats already.