set encoding UTF-8 for settings sample

The install instruction ask people to copy the local settings sample
file and then fill in their information. When your name is entered using
some unicode, django will fail to run because python can not interpret
the content encoding.

* mark sample file as using UTF-8 encoding
* prefix strings with 'u'

Change-Id: Ie3f46168d555994b26c6821751c6c8aa5e7b3c6c