Initial add for the sum of multiples exercise
Small update

Still learning some F# along the way
Adding more functionality
Finished implementation and tests
Refactored back out to separate files
Updated names
Set all tests except the first to Ignore
Merge remote-tracking branch 'origin/sum-of-multiples'
Added and started implementing difference of squares
Finished implementing difference of squares
Merge branch 'master' of https://github.com/jwood803/xfsharp