Merge pull request wp-cli#20 from wp-cli/scaffold-tests-readme-12-8

Update scaffolded tests and README to latest

Merge pull request wp-cli#17 from wp-cli/scaffold-readme-github-11-20

Update scaffolded README and GitHub configuration

Merge pull request wp-cli#15 from wp-cli/update-test-scaffold

Update scaffolded tests to latest

Merge pull request wp-cli#11 from wp-cli/use-trusty

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

Merge pull request wp-cli#8 from drrobotnik/file-exists

Prevents non-existent directories from ending up in list of files to import

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