Fix namespace problem

[nbrinckm]

The code is changed so that any quakeml namespace can be used.
Please review and test.

This fix was meant to be merged into this (https://github.com/ruester/shakyground/blob/master/quakeml.py), so sorry, for spamming.

But anyway it would be great if you could update the code in here, so that we don't need the repository of matthias ruster anymore)

The changes:

• support for valid quakeml files (the old ones are not valid according to the xsd files for quakeml)
• support for the usage of any xml namespace

[ruester]

Opened #4 now, which also contain those changes...