Bug 16701: Translatability: Fix problem with isolated ' in currency.tt

Bug 16701: Translatability: Fix problem with isolated ' in currency.tt

This patch moves markup <span class="ex"> into template variables to
avoid sentence splitting.

To test:
- Apply patch
- Verify that currency administration works as before
  (Home > Administration > Currencies & Exchange rates > Currencies)
- Examine code changes

Signed-off-by: Hector Castro <hector.hecaxmmx@gmail.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>