Issue 1594: DefaultODataBatchHandler doesn't handle urls relative to the
batch endpoint properly.
The root cause is that the base uri of ODataMessageReaderSettings doesn't
end with slash.
The fix is only for v3 and v4 works well for all kinds of urls because
ODL v4 will append a slash in the end of the base uri if there isn't one.
Issue 1941: Parameters Property of SingleEntityFunctionCallNode should
never be null
It is fixed in ODL 6.4
https://aspnetwebstack.codeplex.com/workitem/1941
Issue 2003: ODataBatchHandler should contain more common helpers
https://aspnetwebstack.codeplex.com/workitem/2003