Home page configuration option

Allow users to specify a home page and have High Voltage take care of
the root route and redirect to avoid duplicate content.

* Add configuration option for home_page.
* Add new root route and redirect.
Add spec for testing nil homepage

* Add random for running specs.
* Clear cache between test runs.
* Add context to caching tests for readability.
Remove ruby debugger dependency

Seeing some issues on Travis when trying to install `debugger` gem that
is included with pry-debugger. Removed in favor of standalone `pry` gem.