add method to configure http basic authentication
Add OKComputer.requires_authentication?
if configured to do so, require HTTP Basic authentication to view checks
update readme with OKComputer.require_authentication
add OKComputer.authenticate(username, password) helper method
move authentication into a private controller method
stub out authentication in the controller tests
Merge remote-tracking branch 'origin/master' into authentication

Conflicts:
	app/controllers/ok_computer_controller.rb
make the getters for username and password also be private
Merge pull request #18 from tstmedia/authentication

Add Optional HTTP Basic Authentication to Checks