Add option to #markdown_with_heading to create nav for styleguide
section.

Signed-off-by: Nicole Sullivan <nsullivan@pivotal.io>
Add option to hologram_config to include section nav.

Signed-off-by: Nicole Sullivan <nsullivan@pivotal.io>
Add include_section_nav to default config file

Signed-off-by: Geoff Pleiss <gpleiss@pivotal.io>
Make subnav configurable to top level or all sections

Signed-off-by: Geoff Pleiss <gpleiss@pivotal.io>
Fix tests

- An extra space was added during rebasing that screwed up some tests.

Signed-off-by: Geoff Pleiss <gpleiss@pivotal.io>
Merge pull request #156 from stubbornella/feature/section_nav

Add section navigation