Support multiple categories in ProductListerWidget

[erikssonorjan]

Added list of categories and removed single category.

[erikssonorjan]

The schema also need to be updated. Categories (multiple) should be added and single category should be removed:

<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns="uuid:3e7cc2b0-7f41-4333-b946-faa82a29d979" xmlns:tcmi="http://www.tridion.com/ContentManager/5.0/Instance" elementFormDefault="qualified" targetNamespace="uuid:3e7cc2b0-7f41-4333-b946-faa82a29d979">
  <xsd:import namespace="http://www.tridion.com/ContentManager/5.0/Instance" schemaLocation="cm_xml_inst.xsd"></xsd:import>
  ...
  <xsd:annotation>
    <xsd:appinfo>
      <tcm:Labels xmlns:tcm="http://www.tridion.com/ContentManager/5.0">
        <tcm:Label ElementName="categories" Metadata="true">Categories</tcm:Label>
		...
      </tcm:Labels>
    </xsd:appinfo>
  </xsd:annotation>
  <xsd:element name="ProductListerWidget">
    <xsd:complexType>
      <xsd:sequence></xsd:sequence>
    </xsd:complexType>
  </xsd:element>
  <xsd:element name="Metadata">
    <xsd:complexType>
      <xsd:sequence>
        <xsd:element name="categories" minOccurs="0" maxOccurs="unbounded" type="ECommerceCategory">
          <xsd:annotation>
            <xsd:appinfo>
              <ExtensionXml xmlns="http://www.tridion.com/ContentManager/5.0"></ExtensionXml>
              <tcm:EmbeddedSchema xmlns:tcm="http://www.tridion.com/ContentManager/5.0" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="tcm:21-832-8" xlink:title="E-Commerce Category"></tcm:EmbeddedSchema>
            </xsd:appinfo>
          </xsd:annotation>
        </xsd:element>	
		...
      </xsd:sequence>
    </xsd:complexType>
  </xsd:element>
</xsd:schema>