added :patrons_can_renew to app configs (modified)

Conflicts:
	app/models/app_config.rb
	app/views/app_configs/_form.erb
updated ability.rb with patron renewal option
updated reservation show page based on renewal ability
made items with zero-length max renewal ineligible for renewal (modified)

Conflicts:
	app/models/reservation.rb
Renamed configuration parameter to enable_renewals (modified)

Conflicts:
	app/views/app_configs/_form.erb
broadened restrictions to all roles except superuse
add enable_renewals to strong params
updated schema
set default role and matching view mode in create controller actions
explicitly deny non admins/superusers the ability to change view mode
added validation on view mode permissions in the model
updated validator to just reset the view_mode before saving
set default view mode in schema to 'normal' and updated schema
fixed view mode changes for admins
made renewal redirect to reservation page w/ flash
deleted old renewal views / JS
updating Gemfile.lock for Travis (we need to fix our Gemfile)
fixed indentation of case statement in ability.rb
fixed indentation of 2nd case statement in ability.rb
updated specs to expect renewal to redirect to reservation show view