Fix export format for resx. Fixes #237
Don't have empty values in Resx format. Fixes #238
Forgot to remove test code
Added error message when the validation isn't passed for the first translated string.

Props Japh. see #149
Update resx unittest to reflect changes made in #237
Added Last-Modified/If-Modified-Since for downloading translation files. Props DJPaul. Fixes #236
Change filename for po/mo files. Other formats can be looked into later. Fixes #206
Adding missing translatable strings and some minor code cleanup. Props momo360modena. Fixes #57
Fix possible issue in short handed if statement. Props tschutter. Fixed #229
Add missing translatable strings with ability to change the language. Props atrax. Fixes #137
Add filter to the translation sites of a project. So people can filter/order it. Fixes #177
RTL languages will have their translations from RTL. Fixes #158