Specify an UTF-8 Charset and use an html special character to avoid a malformed tag error in the footer

[elaine-jackson]

This pull request specifies an UTF-8 Charset on all pages. (This is most common and includes emoji support, if the project prefers plain ASCII let me know and I'll amend my PR) and uses an html special character in the footer to avoid a malformed tag error (we have an un-closed <3 tag, this isn't intended to be a tag however some browsers may attempt to parse it and warn or throw an error, using the special character for < fixes this issue).

• [x] PR message includes a link to the relevant issue(s) 💁‍♀️🖇️🧾
• [x] Commit messages are well-formatted (please follow this guide) 📝📐
• [x] New features have test coverage 📋☑️☑️☑️
• [x] The app boots and pronoun pages are served correctly (try lein ring server) 👩‍💻🚀

[morganastra]

This looks great, thanks!