KDM14 — Change MOF XMI version for the specification

Currently the KDM spec references an old XMI version 2.1
The current is 2.4.2
This affects examples in the specification text as well as KDM XMI XSD

Update example to new version of XMI and KDM

The new format of standard references for XMI 2.4.2 schema files is :
XMI namespace URI http://www.omg.org/spec/XMI/20110701
XMI xref URI http://www.omg.org/spec/XMI/20110701/XMI-model.xmi

According to standard format of OMG references, each KDM 1.4 package
has own namespace URI, with the common base
http://www.omg.org/spec/KDM/20160501
followed by the package name.

For example, for KDM Core package
XMI namespace URI http://www.omg.org/spec/KDM/20160501/core
XMI xref core.xsd

Use of references in XSD schema
<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema"
xmlns:xmi="http://www.omg.org/spec/XMI/20110701"
xmlns:core="http://www.omg.org/spec/KDM/20160501/core"
xmlns:kdm="http://www.omg.org/spec/KDM/20160501/kdm"
xmlns:source="http://www.omg.org/spec/KDM/20160501/source" targetNamespace="http://www.omg.org/spec/KDM/20160501/source" >

<xsd:import namespace="http://www.omg.org/spec/KDM/20160501/core" schemaLocation="core.xsd" />
<xsd:import namespace="http://www.omg.org/spec/KDM/20160501/kdm" schemaLocation="kdm.xsd" />

Use of references in KDM XMI document
<?xml version="1.0" encoding="UTF-8"?>
<kdm:Segment
xmlns:xmi="http://www.omg.org/spec/XMI/20110701"
xmlns:core="http://www.omg.org/spec/KDM/20160501/core"
xmlns:code="http://www.omg.org/spec/KDM/20160501/code"
xmlns:kdm="http://www.omg.org/spec/KDM/20160501/kdm"
name="Stereotype Example">