Install via HTTPS in README

By default, installation environments lack Github SSH credentials and
this step fails. Anyone needing to clone via SSH can do so explicitly.

This way, the recommended installation path works out-of-the-box.
Fix Markdown syntax for code literal

The code literal section was missing a closing backtick.
Fix Markdown syntax for ordered lists

Github-flavored Markdown requires an additional indent for code blocks
nested within list items [1].

[1] http://meta.stackexchange.com/questions/3792/how-to-nest-code-within-a-list-using-markdown
Specify sane defaults for demo certificates

Previously, certificate generation expected access to S3.

This shouldn't be required when generating a demo certificate, so we
update the README's sample script to disable S3 uploads.

The sample script now specifies the default demo course_id, instead of a
non-existent course_id.

All command line flags are specified with `--long-options` to make the
options explicit to users, as this is their first exposure to the code.
Update private directory variable
Add note about help options
Merge pull request #19 from stvstnfrd/readme/install

Update README install steps