Upping the GitHub H with the aid of title frontmatter on slides

Since the slide titles can now be explicitly set from the
frontmatter instead of just the raw filename, a good way
to keep the H puffed.

And the YAML all caps as needed.

Not to mention a stray question mark back.
YAML example uses three dashes; Committing requires two T-shirts

All other YAML frontmatter marks use three, keep it consistent
with the rest of examples.

Signup link appears to be the only one loaded with http for its
display. Might as well update to its SSL link.
Merge pull request #178 from randomecho/slides-casing-and-typos

Fix GitHub casing; Normalize use of YAML example, links