Use the proper translation for fetching country names and improve mcc detection.

Use the proper translation for fetching country names and improve mcc detection.

* src/modest-utils.c
  (modest_utils_open_mcc_mapping): allow fetching
  using LC_MESSAGES or LANG. It uses g_strsplit with ":" to try with
  the mcc files for each of the languages or regions you may have
  selected.
  (modest_utils_fill_country_model): first fetch the mcc for LANG to
  detect the current region. Then fetch the mcc for LC_MESSAGES for
  filling the countries list in the proper language (fixes NB#110057).