feat(dinero): Add hasSubUnits method and deprecate hasCents

fix dinerojs#20

Merge pull request dinerojs#19 from sarahdayan/precision

Add precision concept

docs(readme): Add precision regardin browser support

fix(dinero): Use Object.assign transformer for better browser compati…

…bility

fix(dinero#percentage): Use hardcoded 100 (a percentage is always div…

…ided by 100)

fix(calculator#multiply): Fix precision in float multiply method

test(helpers#isFloat): Add property-based tests

test(calculator#multiply): Add unit test for two floats

Merge pull request dinerojs#10 from tarnelope/negative-value-rounding

fix(Update toRoundedUnit to properly round negative values)

Merge pull request dinerojs#12 from scotttrinh/fix-multiply-divide-th…

…rows

fix(dinero): Round intermediate divide and multiply calculations