Note why the frequencies method is so unorthodox
Add rake task to run the tests
FIX don't define sum if it's defined by another gem e.g. active_support
Don't overwrite any Enumerable methods already defined
Coerce BigDecimal back to float for mean and median

Returns floats as the README indicates; Ruby 1.8.7
did this already, the promotion behavior changed
somewhere in the 1.9 series
Allow passing a block to map the input first
Version Bump 1.1.0

- will not overwrite ActiveSupport's sum
- mean/median always return Float
- methods will map first if given a block