[backend] Correct event_name checks in promotion_adjustments_spec
[api] Remove duplicate tests in OptionTypesController spec
Move money spec to core
Refactor Spree::Money's with_currency and no_cents option settings
Insert non-breaking space in Money objects where currency symbol is afterwards to prevent issues as seen in #2634

This commit introduces the to_html helper for Spree::Money objects

Fixes #2634