Merge branch 'improve-error-message' into 'master'

Improve english of error message

See merge request !1284

app/services/files/create_service.rb

@@ -22,7 +22,7 @@ module Files
         blob = repository.blob_at_branch(@current_branch, @file_path)
 
         if blob
-          raise_error("Your changes could not be committed, because file with such name exists")
+          raise_error("Your changes could not be committed because a file with the same name already exists")
         end
       end
     end