Revert WsdlParseException class hierarchy change

I had attempted to unify the different exceptions being thrown throughout the Wsdl parsing code, by modifying WsdlParseException to extend from ConnectionException (instead of java.lang.Exception).  While this worked, it also requires changes to client code, especially the core app, which may not be desirable at this time.  So I have reverted the changes for now. 

Using the jars generated from this build, I successfully built the app on both Mac and Linux machines with a vanilla checkout (no locally modified files).  I verified the partner.wsdl compiles a jar correctly, and I generated several Apex class files using the core app WSDL2Apex feature successfully.

There is one minor bug fix that is piggybacking along as well, to avoid an NPE for one-way operations.