[TYPO3-caretaker] New Feature Retry-Test

[Martin Ficzel]

I added a maxRetryNumber configuration to the test. Now you can define that a failing test 
should imediatly be executed again n-times. The default value is zero. For me this made 
some flickering tests (especially ping and http) behave much more stable.

Question: I implemented and comitted this as a generic feature of the test-record and the 
testrunner. It could be implemented as a feature of the ping and http test-service too. 
What do you prefer.

Regards Martin