Account for accessibility

Add alt tags, title tags, and text to areas where someone with
accessibility issues may struggle to use the website.
Worth noting that using `title` attribute might not be accessible for all users. See Paciello Group's [HTML5 Accessibility Chops: title attribute use and abuse][1] and [Using the HTML title attribute][2].

[1]: http://www.paciellogroup.com/blog/2012/01/html5-accessibility-chops-title-attribute-use-and-abuse/
[2]: http://www.paciellogroup.com/blog/2010/11/using-the-html-title-attribute/