update testing docs

[wouterj]

It needs to be updated with the new db testing methods and also how to test configuration classes.

[dbu]

the PR is merged now.

[wouterj]

well, this issue was also about other Testing component things. I'll try to refactor this this weekend.

[dbu]

this has the 1.1 milestone. does it need to? i think there are more critical things.

[wouterj]

It's not critical (as there are no BC breaks), but all 1.1 features of the Testing component are not documented

[dbu]

ping @wouterj