Initial hieroglyph slides

This configuration does a few things:

* Default html build does not build anything under slides (based on the
  excludes_patterns config in conf.py
* Builds slides as a slides sub directory of the content

NOTE: I had to make a separate doctree directory for each build otherwise sphinx
would complain
Also build slides
Add initial basic intro slide deck (work in progress)
Hide the index but source any files
Enable intersphinx mappings for slides and site content

Also add logic to the build script so that it doesn't fail on the first run.
We'll just assume warnings aren't errors on an initial checkout.
Use bold instead
Add slides based on Carlos's intro slides
Add website and doc tag
Use 'in-class' instead
Reword this slightly
Cleanup and unify slide
Merge pull request #4 from osuosl/ramereth/initial-slides

Initial hieroglyph slides