Making hashes node optional as devices will not have hashes.

Author: stevespringett

schema/bom-1.0.xsd

@@ -49,7 +49,7 @@
                     scope will be assumed.</xs:documentation>
                 </xs:annotation>
             </xs:element>
-            <xs:element name="hashes">
+            <xs:element name="hashes" minOccurs="0" maxOccurs="1">
                 <xs:complexType>
                     <xs:sequence minOccurs="0" maxOccurs="unbounded">
                         <xs:element name="hash" type="bom:hashType"/>