Small docblock fixes

Signed-off-by: Dries Vints <dries.vints@gmail.com>
Fix Str::slug() separator flip.
Refactored by removing an extra line of code

spl_autoload_register function already returns True on success and False on failure.
Check Jsonable interface in Response::json method. Fixes #1947.
Merge pull request #1946 from KaneCohen/str3

Fix Str::slug() separator flip.
Merge pull request #1917 from driesvints/dv/small-dockblock-fixes

Small docblock fixes
Fix a bug with JSON responses.
merge 4.0 branch to master. fix conflicts.
Allow macros on the Response class.
Merge branch '4.0'