Add seo flags

This pull request adds a new block template to switch_language called
seo_flags, similar to the flags template, except that:
- the destination link of the flags is the final url of the translated
  pages
- the ccm-multilingual-switch-language-flags-label is printed out only
  if $label is not empty.
redirect to language

if the locale not in db, search for language and redirect to the specific language
Merge branch 'add-seoflags' of https://github.com/mlocati/addon_internationalization
modifying getLanguageText in section model to not fail for languages without msIcon