Replace pre-packed WSC JARs with code gen from WSDLs

This replaces the instructions for manual WSDL consumption with automatic code generation via WSC as part of the Maven build. With this change, any `*.wsdl` files placed in the `src/main/wsdls` dir are automatically consumed with WSC and the generated source files are placed in `target/generated-sources/wsc`. The generated source files are then compiled as part of the project (but not checked in, since they are in `target`). 

Caveats / Notes:
 - This is using WSC 29.0, but the 30.0 WSDLs, which should not be a problem unless there is some new WSDL parsing the WSC 30.0 you're relying on.
 - This is using  `maven-antrun-plugin` to do the generation. WSC should really have a custom Maven plugin for this sort of thing instead of publishing those pre-packaged JARs in Maven Central. If that happens, the ANT stuff can be replaced with a real plugin.
 - This method works much better with the Enterprise WSDL since it will vary by org and can just be generated on the fly; however, I question your use of the Enterprise WSDL at all, since this project should be designed to work for any org. Why are you not using the Parter WSDL?