Added error template, added blog title to title tag.

[dannyvankooten]

Hi Dale,

Thank you for your work on Uno, it's a real beauty!

I made some small modifications to the theme which I thought you may like.

• Added an error template for 404 errors etc.
• Added the blog title to the <title> tag.

Homepage: Blog Title Post pages: Post Title - Blog Title Error pages: Error Title - Blog Title Tag pages: Tag Name - Blog Title