Add Test for 441-A6

Adds the missing test for 441-A6. The test currently fails in the RI
for locales with a trailing zero (eg "3.5-") because
`DefaultMonetaryAmountFormat.positiveTokens` parses successfully and
`DefaultMonetaryAmountFormat.negativeTokens` is never used.
Merge pull request #11 from marschall/441-A6

Add Test for 441-A6