Fix an error where the value returned was not in double's scope

When provided with Double.MAX_VALUE, the formatting method breaks completely - it returns Double.POSITIVE_INFINITY, which other methods can't really parse. (At least, BigDecimal doesn't like it)

This pull request stops the formatting of such numbers.
Merge pull request #3 from Acrobot/patch-1

Fix an error where the value returned was not in double's scope