test for exporting yml in a valid I18n undestandable format.

en:
  "home.header.title": "Foo"

Will not be found by I18n. The dot notation needs to be converted to a nested hash.

The expected format is
:en:
 :home:
   :header:
       :title: "Foo"
convert dot notation to nested hash when exporting.

thanks to http://stackoverflow.com/questions/4364891/how-to-transform-dot-notation-string-keys-in-a-hash-into-a-nested-hash