Fix test warnings

Fixed:
[deprecated] I18n.enforce_available_locales will default to true in the future. If you really want to skip validation of your locale you can set I18n.enforce_available_locales = false to avoid this message.
/Users/user/woven/github/gollum-lib/test/test_file_view.rb:57: warning: class variable access from toplevel
test/unit warning: method #<Class:0x007fb591a50c00>#test_title_from_filename_with_normal_contents is redefined
test/unit warning: method #<Class:0x007fb591a50c00>#test_title_from_filename_with_html_contents is redefined
test/unit warning: method #<Class:0x007fb591a28f98>#test_create_and_read_non_latin_page_with_anchor is redefined