refactor navbar spacer

replace per-template spacers with one in index.html
(see http://twitter.github.com/bootstrap/components.html#navbar)
improve REST API for related photos

for photos attached to species, trips, locations, make sure to include
species, trips, locations attached to photos; also ensure to pass along
value of image_filename()
compact page titles

make page titles smaller, less whitespace and smaller fonts
use carousels for photos in mobile app

create new template that shows photos using bootstrap carousel; replace
old showPhoto template with wrapper function that invokes carousel
template.
add countries model

add model for countries
add country_id foreign key to state table
add scaffolding for create/update/edit/delete countries
fix functional tests for countries