Merge pull request wp-cli#18 from wp-cli/scaffold-tests-readme-12-8

Update scaffolded tests and README to latest

Merge pull request wp-cli#16 from wp-cli/scaffold-readme-github-11-20

Update scaffolded README and GitHub configuration

Merge pull request wp-cli#14 from wp-cli/update-test-scaffold

Update scaffolded tests to latest

Merge pull request wp-cli#10 from wp-cli/use-trusty

Use `dist: precise` for PHP 5.3, `dist: trusty` for everything else

Merge pull request wp-cli#7 from wp-cli/clarify-bundled

Clarify this command as a bundled command

Use PSR-4 autoloading of existing classes; add remaining test files