add testing gems to app
create listing model
factory for listing
test for listing valid with attributes
listing not valid without a role
listing not valid without a company
listing not valid without a location
create listings controller
index action for listings
test for rendering index template
implement show action for listings
test show action rendering show template
new action for listings implemented
test for get new rendering new template
implement create action for listings
test for redirecting to show on listing create
implement listing create with invalid attributes
listing re render new template on invalid attributes create
refactor routes