changed locale to use string since enum description is broken.

added tests for setting locale via cookie or accept-language header. #329

replace %(form) and %(fields) with {{form}} and {{fields}} to be
consistent across strings.

reset kujua_locale cookie when deleting session.
added translation updates from Marc and Ranju. #335
Merge branch 'develop' of github.com:medic/kujua-lite into develop