Wiki breadcrumb added

I needed it, so I made it ;o)

By the way, I'm not sure that redmine wiki's breadcrumb is working like this. The important thing is that there is a breadcrumb, we can always change it later.

The .gitignore is a mean to not commit .mo files while translating, I don't know if you can merge only some files of this pull request or not. If not, I can change the .gitignore back.