Implement Konjak.parse
Add rspec-its to gemspec
Add test for Konjak.parse, that returns tmx with correct version
Implement Tmx#header, Tmx#body
Implement header attributes
Implement Header#notes
CleanCode
Implement Header#user_defined_encodings
Implement Header#properties
Implement body#translation_units
Clean describe
Implement TranslationUnit attributes
Impement TranslationUnit#variants