Testing must take place in the en-US locale since tests are written for it.
This solve the behat failures for checking promotional discounts (most locales
show negative number as: -$100.00,  en-US shows ($100.00)
Fixes #853 along with other issues.
Merge pull request #1014 from mykehsd/feature/I#853-NumberformatterTesting

Numberformatter intl bugs with negative numbers