Thrift: Finish namespace generation from xsd_namespace command

Thrift: Finish namespace generation from xsd_namespace command

In .thrift file:

xsd_namespace "http://api.facebook.com/v1"

Turns up in the xsd output as:

<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema"
 targetNamespace="http://api.facebook.com/v1"
 xmlns="http://api.facebook.com/v1"
 elementFormDefault="qualified">

to properly accommodate our generated xml

Thank you, Slee.

Reviewed By: mcslee

Test Plan: sandbox

Revert Plan: revertible

Notes:

git-svn-id: https://svn.apache.org/repos/asf/incubator/thrift/trunk@664960 13f79535-47bb-0310-9956-ffa450edef68