Gemfile: specify ruby 1.9.3
Add Procfile for Heroku's Foreman runner
config.ru: mark STDOUT as no-flush for Heroku
MySQL -> PostgreSQL
Layout: use img helper for search_glass
assets:precompile for Heroku

Heroku will run `rake assets:precompile` automatically on deploy,
so we define that task as an alias to `assets:compile`.

Additionally, `assets:compile` didn't create missing directories, so
it would bomb on Heroku.

Conflicts:
	lib/tasks/compile_assets.rake