Add bower

FYI, this commit was originally before the commit that added gulp, but
when I reordered them, I forgot to move the gulp tasks later in the
commit sequence to match. Interactive rebase really bites you when you
get careless.
Add min
Add frontend markdown deps

These are the core dependencies we'll use to display markdown.
Provide basic wiki template

It lives! Basic wiki page template rendering!
Better error templates

Only a little bit better, but still better
Implement basic markdown rendering

We're talking really basic here. Prism isn't cooperating right now, but
I can see at least two reasons that it wouldn't work:
- for some reason, marked generates class="lang-foo" instead of the
  standard class="language-foo". I don't understand why so many markdown
  renderers flout the expectations here.
- I'm not including the prism css, so even if the highlighting did work,
  it wouldn't have any visual effect.

Ah well. We'll fix that shortly.
Correct language prefix

This undocumented marked option is very useful. At least I didn't need
to define a custom renderer for code blocks.
Refactor env config in gulpfile

This commit also adds a GOOSE_DEV for template recompilation. Might also
be useful for other things in the future.
Refactor templates and fix highlighting

Highlighting has to be fired explicitly on each code block because the
markdown is getting rendered after prism itself is loaded. Also did some
template tweaking, moving the entire <body> into the yielded section.
Remove main-bower-files

Prism's default build includes very few languages. We can fix that by
building prism ourselves. In that case, there's no need to find bower
files automatically, so I'm comfortable with removing the dependency and
hard-coding the paths.