Fix some bugs in edksetup.sh

Fix some bugs in edksetup.sh
1, WORKSPACE environment in unix-like system can be obtained automatically as edksetup.bat in window's environment.
2, XMLBEANS_HOME environment in unix-like system should be also check as edksetup.bat in windows's environment.
3, In some unix-like system like darwin's system, system environment should be export to user's environment explicitly, this behavior is different in microsoft windows's platform.

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@849 6f19259b-4bc3-4df7-8a09-765794883524