Rulesets: Add XSD schema tags (PHPCS 3.2+/3.3.2+)

As of PHPCS 3.2.0, PHPCS includes an XSD schema for rulesets which defines what can be used in the XML ruleset file. In PHPCS 3.3.0 a new array format for properties was introduced and as of PHPCS 3.3.2, the new array format is now also covered by this schema. This commit adds the schema tags to the `ruleset.xml` file and the example rulesets.

Author: jrfnl

Security/ruleset.xml

@@ -1,4 +1,4 @@
 <?xml version="1.0"?>
-<ruleset name="Security" namespace="PHPCS_SecurityAudit\Security">
+<ruleset xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" name="Security" namespace="PHPCS_SecurityAudit\Security" xsi:noNamespaceSchemaLocation="https://raw.githubusercontent.com/squizlabs/PHP_CodeSniffer/master/phpcs.xsd">
  <description>Security related coding standard.</description>
 </ruleset>

example_base_ruleset.xml

@@ -1,5 +1,5 @@
 <?xml version="1.0"?>
-<ruleset name="PHPSecurity">
+<ruleset xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" name="PHPSecurity" xsi:noNamespaceSchemaLocation="https://raw.githubusercontent.com/squizlabs/PHP_CodeSniffer/master/phpcs.xsd">
  <description>Rules for standard PHP projects</description>
 
 <!-- Code Reviews Rules -->

example_drupal7_ruleset.xml

@@ -1,5 +1,5 @@
 <?xml version="1.0"?>
-<ruleset name="Drupal7Security">
+<ruleset xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" name="Drupal7Security" xsi:noNamespaceSchemaLocation="https://raw.githubusercontent.com/squizlabs/PHP_CodeSniffer/master/phpcs.xsd">
  <description>Rules for Drupal 7 projects</description>
 <!-- Code Reviews Rules -->
 <!--