Display warning when multiple components have the same name.

Signed-off-by: Geoff Pleiss <gpleiss@pivotal.io>
Add configurable option to exit on warnings.

Signed-off-by: Bebe Peng <bpeng@pivotal.io>
Add docs for exit_on_warning option to README

Signed-off-by: Bebe Peng <bpeng@pivotal.io>
Fix errors on CI

- We were experiencing errors because we were not cleaning up tests that
  used the DisplayMessage.exit_on_warning! method

Signed-off-by: Bebe Peng <bpeng@pivotal.io>
Merge pull request #167 from gpleiss/feature/configurable_warnings

Configureable option for exiting on warnings
Merge pull request #166 from bebepeng/feature/duplicate-name-warning

Display warning when multiple components have the same name.
Add ability to reference link to other components in docs.

To link to the "typography" component on the "css.html" page from
another component's docs, you can now do
`[link to typography][typography]`
instead of
`[link to typography](/css.html#typography)'.
Add docs for component reference links