Fix ZF-11921: Race condition in plugin loader include file cache

This fixes the race condition described at:
http://framework.zend.com/issues/browse/ZF-11921

For the race to disappear each and every line is made completely independent from the others. This is the reason why every line includes its own php open and close tag, and no file_get_content() is made, and the file is opened in append only mode.

To prevent the insertion of duplicates lines, a fast non blocking lock is made and kept until the end of the request, thus the static $h.

Tested on a highly concurrent server without a problem.
Code cleanup
Minor fix in PluginLoader.php
fixes #162. Back porting with a cut and paste
Added JSON_UNESCAPED_UNICODE and JSON_UNESCAPED_SLASHES to encoding GCM Data to JSON
Added PHP 5.6 and HHVM to Travis
Merge pull request #285 from mhujer/travis-hhvm

Added PHP 5.6 and HHVM to Travis
Fix for XML XXE/XEE potential attacks
Added heuristic check for XXE/XEE attacks with PHP-FPM
Merge branch 'security/zf2014-01'

Resolves ZF2014-01 - XXE/XEE vulnerabilities
Security fix for OpenID
Merge branch 'security/zf2014-02'

Resolves ZF2014-02 - Potential security issue in login mechanism of Zend_OpenId consumer
[1.12.4] Release readiness

- Added security announcements to README
- Updated `Zend_Version::VERSION`
Merge branch 'releases/1.12.4'

1.12.4 readiness
Fix OpenId Consumer docblock broken in f6606ff
Merge pull request #290 from mhujer/fix-openiddocblock

Fix OpenId Consumer docblock broken in f6606ff
Anonymous function rewritten as static one to maintain compatibility with PHP 5.2
Merge pull request #293 from mhujer/fix-anonymous-f

Fixes #292 - Anonymous function rewritten as static one to maintain compatibility with PHP 5.2
Check that pathinfo() has returned an extension

Prevent the notice that is generated when pathinfo() doesn't return an
'extension' element in Zend_Validate_File_Extension.

Fixes #287
Merge pull request #294 from akrabat/issue-287

Fixes #287 - Check that pathinfo() has returned an extension