Initial localization code

Added resx files, default (English) and fr one.
Adapted unit tests to use the default culture, added simple localized
tests.
Fixed the "and" issue (was not localized yet)

Added a resource string for the "and" keyword. I suspect this might be
improved later by having another mechanism to handle the last unit, but
it can probably be postponed to a language where this is an actual
issue.
Moved the localized unit tests in a sub directory.
Merge pull request #5 from Pvlerick/master

Initial localization code