fix FileEngine, divergent behavior when debug is off or on
Fix some docblock typo
Merge remote-tracking branch 'origin/2.6' into 3.0

Conflicts:
	lib/Cake/Model/Model.php
	lib/Cake/Test/Case/Model/ModelValidationTest.php
	src/Cache/Engine/RedisEngine.php
	src/TestSuite/TestCase.php
	tests/TestCase/Cache/Engine/MemcachedEngineTest.php
	tests/TestCase/Cache/Engine/RedisEngineTest.php
	tests/TestCase/TestSuite/TestCaseTest.php
Fix some docblock type
Fix namespace in docblock.
Merge pull request #4768 from darxmac/cache-consistent-behavior

fix FileEngine, divergent behavior when debug is off or on