Implements testFindByIdFrom()

This pull request will implement the findByIdFrom() test. This is the first phpunit test I've written but it seems to work as it should. See https://travis-ci.org/NicNLD/wolfcms/builds - as from build 11, the results are as expected.

This test should be a basic indicator of the cross-DB functioning of my record finder. Other tests should probably be written as well to test the functioning more thoroughly.