Bug fixes

Hi, fixed a few bugs that bothered me,
hope it helps!

1. In client.js, for rpc style -- allow method to not have any parameters.
2. In wdsl.js  --- fixed bug, if the xml is returned in a soap response, there were no whitespace around attributes in it.
3. In wdsl.js  --- allow extra headers in open_wdsl (should be passed as exHeaders option).