Clean up test-suite using pywps test utils

[cehbrecht]

Description

The current test suite has copied util methods form pywps, like get_output:

emu/tests/common.py

Line 30 in 3502572

def get_output(doc):

We should make the pywps test utils public available. We should also have a look at Get and Post test examples.

Common test tools should be part of pywps and not copied by each WPS bird.

Additional Information

See also PR #48.