Update application.rb to use Action*::Railtie

I'm not sure where ActionController::Engine and ActionMailer::Engine came from -- I don't see them in the Rails release-3.0, release-3.1 or release-3.2 branches. I suspect Railtie is the right constant to use instead.
Fixed the contributors link in the README.
Merge pull request #24 from parndt/patch-2

Fixed the contributors link in the README.
Updated README

* Fixed unclear instruction regarding capybara/rspec to capybara/rails
Added config setting to load test db structure from a .sql file
Rejigging sql schema support.
Updating HISTORY to track recent-ish changes.
Merge remote-tracking branch 'cbeer/patch-1'
Credit for patch from Chris Beer.
Noting Niklas Cathor's helpful Cucumber issue.
Version file is overkill.
0.3.3
Place class definitions inside module Combustion.

This allows libraries to selectively load parts of Combustion without
having to load the entire thing. For example, if you wanted to use the
Database class then you can just use:

require 'combustion/database'

Previously this would require:

require 'combustion'
require 'combustion/database'

As you would receive the following error message:

combustion/lib/combustion/database.rb:1:in `<top (required)>': uninitialized constant Combustion (NameError)
Combustion now loads, by default, less of the Rails stack -- only ActiveSupport.

If you want to automatically load it all as before then use [combustion-rails](https://github.com/pat/combustion-rails).

Fixes #29
Make mass-assignment setting match rails defaults
Updating HISTORY.
Railties is required and config.active_record may not always be available.

Also stops Combustion.initialize! requiring all modules by default.
Noting how other gems impact the load order.