Added unit test for getPrefix method
Remove unused code
Added unit tests for some Str methods (lower, upper, limit, length methods.)
Merge pull request #5804 from lucasmichot/dead-code

[4.2] Database : remove unused code
test values changed
Fix validator docblock
make LogTransport work with custom implementations of PSR LoggerInterface
Remove last duplicate unset
Extract file validation method
Remove useless else
Fix formatMessage docblock
Allows FormRequest to handle input and files
clean up provider a bit
Query grammar should not explode segments on alias
Tweak user behavior.
ease saving of models without updating timestamps
Remove useless $app arguments in bindShared
Fix redirectToAction method
Add getJsonOptions to JsonResponse
Add JSONP function to reponse facade