Changing default locale to "en_US.utf8"

There was positive feedback regarding [this change in the forums](http://boards.openpandora.org/topic/14762-some-asorted-small-proposals-for-the-next-superzaxxon/) and I know no reason why someone wouldn't want to use Unicode.

I [started a thread](http://lists.linuxtogo.org/pipermail/angstrom-distro-users/2013-November/004218.html) to find out the Angstrom way of setting a locale, but an old thread suggests the [profile.d way](http://lists.linuxtogo.org/pipermail/angstrom-distro-devel/2007-May/000309.html) and I cannot find much info in the wiki. Documentation of Angstrom is not even close to the quality of other distro such as ArchLinux.