Ignore RuntimeException

RuntimeException is thrown at race condition.
However, since for the processing at Garbage Collection, other processes
is determined that the expired.
this process is acceptable to ignore the RuntimeException even if there is
missing file.
Merge pull request #4304 from mtak3/ignore_exception_cache_file_engine

Ignore RuntimeException
Optimize FileEngine::gc()

SplFileObject constructor throws an exception if the file does not exist or is a directory.
Merge pull request #4322 from majna/master-file-engine

Optimize FileEngine::gc()
HttpSocket: not overwriting auth header if it is set in request configuration
Merge pull request #4331 from jeremyharris/master

Fix HttpSocket multiple auth requests
Preventing multiple iterations
Merge pull request #4353 from karmicdice/patch-1

Prevent infinite loops by rendering a flash element inside a flash element.

Fixes: #4350
Fix 0 index not being properly parsed for files.
Add test for #4309

The Router internals don't handle // which is good.
fix failing testLogError
Merge pull request #4373 from mstra001/master

fix failing testLogError
Fixes #2707

When the first variable argument = null, but there are more arguments given.
Added testcases to show the change (to fail before the fix)
Merge pull request #4366 from hmic/ticket#2707

Fixed i18n __*() bug
Fix CURRENT_TIMESTAMP being stored as a default value.

When reflecting timestamp columns in MySQL current_timestamp comes back
as the default value. This causes insertion errors later on as
'current_timestamp' is an invalid value for timestamp columns.

Refs #4184
Fix CS.
Merge pull request #4386 from cakephp/issue-4184

Fix CURRENT_TIMESTAMP being stored as a default value.
Update TagFixture.php

Updated the tag fixture so that it doesn't break `CakeSchema::_arrayDiffAssoc()`
Merge pull request #4403 from davidyell/patch-6

Update TagFixture.php
session bugfix