Add the announcements and administator interface to edit it

[Mjacks3]

Pretty open-ended interpretation for now until we implement the admin user functionality. Basically, make the space that will be used for the announcement bar. Whatever looks right to you?

[alexander-bauer]

Ideas for this: Administrators can see a textbox populated with plaintext, which gets stored in the database, and rendered into HTML on the front page of any signed-in user. This could be a simple markup format like Markdown, which we can store verbatim in the database, and then render dynamically.

[alexander-bauer]

@Mjacks3 They desperately need restyling, but the announcements are now shown on the front page.