Merge "Bump required PHP version to 5.5.9"

diff --cc RELEASE-NOTES-1.27
Simple merge

diff --cc composer.json
index d319171,6e9594c..0b50c2a
--- 1/composer.json
--- 2/composer.json
+++ b/composer.json
@@@ -21,9 -21,9 +21,9 @@@
                "ext-iconv": "*",
                "liuggio/statsd-php-client": "1.0.18",
                "mediawiki/at-ease": "1.1.0",
 -              "oojs/oojs-ui": "0.15.2",
 +              "oojs/oojs-ui": "0.15.3",
                "oyejorge/less.php": "1.7.0.10",
-               "php": ">=5.3.3",
+               "php": ">=5.5.9",
                "psr/log": "1.0.0",
                "wikimedia/assert": "0.2.2",
                "wikimedia/base-convert": "1.0.1",