Use non breaking spaces for currency symbols and thin-space for grouping.

This changeset uses non-breaking spaces (U+00A0) to separate money amounts and currency symbols where applicable to prevent ugly linebreaks in money values in print/web.
I also added the thin space (U+2009) as default group separator as per [official SI recommendation](http://www.bipm.org/utils/common/pdf/si_brochure_8_en.pdf#page=133).

To prevent any accidental changes to hese whitespace changes, I used their ``\u`` escaped versions in strings.

The testcases have been updated to reflect these changes.