Support new versions of Exchange

[henrywright88404]

as proposed by pjropachev on the official api issue

From my point of view the following several things that should be done:

Support new versions of Exchange; The current list of versions from Services.wsdl (Office 365):

<!--  Enumeration of Exchange Server versions  -->
<xs:simpleType name="ExchangeVersionType">
    <xs:restriction base="xs:string">
        <xs:enumeration value="Exchange2007"/>
        <xs:enumeration value="Exchange2007_SP1"/>
        <xs:enumeration value="Exchange2009"/>
        <xs:enumeration value="Exchange2010"/>
        <xs:enumeration value="Exchange2010_SP1"/>
        <xs:enumeration value="Exchange2010_SP2"/>
        <xs:enumeration value="Exchange2012"/>
        <xs:enumeration value="Exchange2013"/>
        <xs:enumeration value="Exchange2013_SP1"/>
        <xs:enumeration value="Exchange2015"/>
        <xs:enumeration value="Exchange2016"/>
        <xs:enumeration value="V2015_10_05"/>
        <xs:enumeration value="V2016_01_06"/>
        <xs:enumeration value="V2016_04_13"/>
        <xs:enumeration value="V2016_07_13"/>
        <xs:enumeration value="V2016_10_10"/>
        <xs:enumeration value="V2017_01_07"/>
        <xs:enumeration value="V2017_04_14"/>
        <xs:enumeration value="V2017_07_11"/>
        <xs:enumeration value="V2017_10_09"/>
        <xs:enumeration value="V2018_01_08"/>
    </xs:restriction>
</xs:simpleType>