feat(missingFallbackDefaultText): enables a feature to return a default text for displaying in case of missing translations including fallback stack

In case you have defined a missingTranslationHandlerFactory, you now have the possibility to define a return value which is set instead of the translationId.
This gives a lot of flexibility for certain use cases.
Example factory:
        $provide.factory('customTranslationHandler', function () {
          return function (translationID, uses) {

          };
        });
docs (custom-error-handler): Add documentation for using default return value
fix(): fix npe on empty strings (trim())

solves #435
solves again #281, #281, #298
feat(messageformat-support): enhancing for sanitization like default

solves #441

This adds the same support for basic escaping like the default
interpolation service.
docs(guide/uk,ru): Multiple translation ids

Add docs about multiple translation ids to Ukrainian and Russian versions of the guide
docs(guide/uk,ru): Remove deprecated docs for default interpolation

Removes deprecated docs about default interpolation from Ukrainian and Russian versions
of the guide.
docs(guide/uk,ru): Replacement text in error handler

Adds info about default replacement text in custom error handler to Ukrainian and Russian
versions of the guide.
fix(translateInterpolator): make it work with 1.3-beta

this commits fixes a bug that was introduced with angularjs 1.3-beta-6
it ensures that there's always at least an empty object for interpolate
params
Performance improvement by limiting calls to localStorage.getItem().
docs(guide/11_custom-storages) : bad link to chapter Storages
docs(guide) : Docs in french

The first part of the guide translated into french (more will come to the end of May)