Add failure scenario with non-ascii-tag
Don't parameterize non-ASCII tag

Because `'☆☆☆'.parameterize` returns `''`
ruby 1.9.3 compatibility
Merge remote-tracking branch 'fukayatsu/non-ascii-tag'

Conflicts:
	lib/middleman-blog/tag_pages.rb
Apply UTF-8-friendliness patches to all uses of #parameterize