Added feature requested in PROV-485 and more

Actually reimplemented the Currency attribute type using Zend_Locale
and friends. You can now enter your currency using the decimal rules of
your UI locale, i.e. Americans can (and should) use $10,000.00 and
others can use notations like 10.000,00 EUR. The currency value output
also uses the same rules so if you switch between UI locales, the
display will adapt while the value that is actually stored remains a
pair of a plain old float and a 3-digit currency code.
Catch exception

You actually can't use the US decimal format 10,000.00 for numbers if
your UI locale is set to de_DE. Always use the decimal format for your
locale.

(We rely on Zend to get this right)
Merge pull request #38 from collectiveaccess/PROV-485

PROV-485