Test all versions of PHP, with WP trunk
Add documentation on testing/developing
Removed test support for multiple WP versions.
Merge pull request #84 from tierra/continue-unit-testing-structure

Removed test support for multiple WP versions.
Merge branch 'master' into continue-unit-testing-structure
Shallow-clone WP for testing

Props @osiux
Merge pull request #76 from WP-API/continue-unit-testing-structure

Continue creating unit testing structure