Fix codesniffer issues

Author: tvdijen

phpcs.xml

@@ -16,6 +16,11 @@
         <exclude-pattern>**/EncryptedAssertion.php</exclude-pattern>
     </rule>
 
+    <!-- Ignore files with side effects that we cannot fix -->
+    <rule ref="PSR1.Files.SideEffects">
+        <exclude-pattern>src/_autoload.php</exclude-pattern>
+    </rule>
+
     <!-- Lines can be a little bit longer before they break the build -->
     <rule ref="Generic.Files.LineLength">
         <exclude-pattern>src/SAML2/Assertion.php</exclude-pattern>

src/SAML2/Certificate/Key.php

@@ -14,8 +14,10 @@
 class Key implements \ArrayAccess
 {
     // Possible key usages
-    const USAGE_SIGNING = 'signing';
-    const USAGE_ENCRYPTION = 'encryption';
+    public const USAGE_SIGNING = 'signing';
+
+    public const USAGE_ENCRYPTION = 'encryption';
+
 
     /**
      * @var array

src/SAML2/Configuration/PrivateKey.php

@@ -12,8 +12,10 @@
  */
 class PrivateKey extends ArrayAdapter
 {
-    const NAME_NEW     = 'new';
-    const NAME_DEFAULT = 'default';
+    public const NAME_NEW     = 'new';
+
+    public const NAME_DEFAULT = 'default';
+
 
     /**
      * @var string