Update transifex config to remove unneeded language mappings

android, qt, tranxifex all have different ideas on how languages
and locales should pose themselves. It is not relevant for  most
languages where we only have one locale, like Turkish. But if we
have different ones or different scripts, we need to tell  while
downloading updates where to look for them.

this updates the internationalization doc with explanation about
transifex language mapping and removes duplicate language files

solves #888