Update exceptions used in cache engines.
Fix tests.
Update exception in log classes.
Removing leading backlash in namespace use statement.
Update exception type.
Moving File and Folder to their own namespace
Add missing use statement.
Merge pull request #4437 from cakephp/3.0-exceptions

Update exceptions used in cache engines.
Merge pull request #4447 from cakephp/3.0-filesystem

3.0 - Moving File and Folder to their own namespace
Merge remote-tracking branch 'origin/3.0' into 3.0-move-time

Conflicts:
	config/bootstrap.php