Allow Hash element of BaseFileComplexType to be unbounded

[burnalting]

In a number of scenarios, a file may have mutliple hashes, perhaps both cryptograpgic and fuzzy (similarity). As a result, the Hash element of BaseFileComplexType should be unbounded to support this. A'la

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<xs:element name="Hash" type="evt:HashComplexType" minOccurs="0" maxOccurs="unbounded">
   <xs:annotation>
      <xs:documentation>Describes the output of a hash function and the type of has function used.</xs:documentation>
   </xs:annotation>
</xs:element>
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