Set default locale settings

The file /etc/default/locale is initially empty. Also, switching the language in phosh settings leaves the file unchanged.

Due to this issue, libphonenumber can't perform number validation and formatting.

Related issues:

• closes chatty#201 (closed)
• closes chatty#204 (closed)

Doing a 'dpkg-reconfigure locales' and 'locale-gen' creates the entries in default/locale, and libphonenumber works as expected.