wps.py: allow multiple outputs and some fixes ...

I'm using wps.py together with PyWPS. 

With the following patch it is now possible to get multiple outputs (commit 846fc2753c48b8f2ad781533fa8d5fbfa294bead). I have added the wps-climdaps.py example to show the usage of this.

It is now possible to parse status message and percentCompleted from response (commit 5fef89d53fbb02ff67917f3fa2fdbf2ba0e5ccab and  619569890e67b82edbe557927b876ac2dc83da14).

I have fixed the namespace of the execution error response (commit ecf5d4f3a110c0489e47b10c0025a6b09ae59a03)

Maybe you find these changes useful and would like to integrate them.

Cheers
Carsten