Fixed a bug in the script - missing % on a WORKSPACE declaration. Also, added an...

Fixed a bug in the script - missing % on a WORKSPACE declaration.  Also, added an argument, skip, that will skip building tools and re-setting the PATH. executing edksetup skip sets WORKSPACE, FRAMEWORK_TOOLS_PATH, CYGWIN_HOME (if c:\cygwin exists) and the CLASSPATH.  This arg was added so that folks who might run the program more than one time from the same command window do not end up with a PATH environment that exceeds the max number of characters.

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@456 6f19259b-4bc3-4df7-8a09-765794883524