Added caching to the categories

Signed-off-by: Steven Magelowitz <steven.magelowitz@gmail.com>
Merge pull request #68 from massmetrics/cache

Added caching to the categories
Updated @categories to pull in only unique names
Updated caching for categories
Removed caching from category show page
added how it works section to instructions page
Merge pull request #69 from massmetrics/hiw

added how it works section to instructions page
removed index route