Various fixes

not quite sure how the bundle currently works at all without https://github.com/liip/LiipTranslationBundle/commit/c4562eb773b7d53bf983d47829d1a88244ce9f1e
this has potential for a bc break. @jeanmonod can you check if there is a problem for you?

the correct naming convention would make this `liip_translation.xliff.loader` (actually `liip_translation.loader.xliff` probably)