Add SOAP examples, with failing test for Issue #4

tests/dump-output/soap

@@ -0,0 +1,16 @@
+SimpleXML object (1 item)
+[
+	Element {
+		Namespace: 'http://schemas.xmlsoap.org/soap/envelope/'
+		Namespace Alias: 'soap'
+		Name: 'Envelope'
+		String Content: '
+    
+    
+'
+		Content in Namespace soap
+			Namespace URI: 'http://schemas.xmlsoap.org/soap/envelope/'
+			Children: 2 - 1 'Body', 1 'Header'
+			Attributes: 0
+	}
+]

tests/input/soap.xml

@@ -0,0 +1,15 @@
+<?xml version="1.0" ?>
+<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
+    <soap:Header>
+        <s:credentials xmlns:s="http://example.org/security">
+            <username>test</username>
+            <password>letmein</password>
+        </s:credentials>
+    </soap:Header>
+    <soap:Body>
+        <tns:DoSomething xmlns:tns="http://example.org/some-soap-service">
+            <from>A</from>
+            <to>B</to>
+        </tns:DoSomething>
+    </soap:Body>
+</soap:Envelope>

tests/tree-output/soap

@@ -0,0 +1,15 @@
+SimpleXML object (1 item)
+[0] // <soap:Envelope>
+	->children('soap', true)
+		->Header[0]
+			->children('s', true)
+				->credentials[0]
+					->children('', true)
+						->username[0]
+						->password[0]
+		->Body[0]
+			->children('tns', true)
+				->DoSomething[0]
+					->children('', true)
+						->from[0]
+						->to[0]