Fix XML deserialization visitor

Allow public_property setter when xmlAttribute, xmlValue or xmlCollection is defined too.

Update XmlDeserializationVisitor.php

Fix elseif syntax.

Update XmlDeserializationVisitor.php

Fixed issue with xmlAttribute property was set to null even though the attribute was missing in xml.

Fixed issue with xmlAttribute property was set to null even though the attribute was missing in xml.
Merge branch 'patch-1' of github.com:zebraf1/serializer into patch-1

Conflicts:
	src/JMS/Serializer/XmlDeserializationVisitor.php