Support for Enumeration Flags (OData v4)

[philcarbone]

The ability to support IsFlags Enums for OData v4 Client <-> Server interaction.

https://github.com/jaystack/jaydata/issues/195#issuecomment-313550736

Example MataData:

<EnumType Name="RequestNotice" IsFlags="true">
    <Member Name="None" Value="0"/>
    <Member Name="OneHour" Value="1"/>
    <Member Name="TwoHours" Value="2"/>
    <Member Name="FourHours" Value="4"/>
    <Member Name="EightHours" Value="8"/>
    <Member Name="TwelveHours" Value="16"/>
    <Member Name="TwentyFourHours" Value="32"/>
</EnumType>