[product: zaphod][project: zaphod-v0.3]: No hardcoded info in test_download.py

SYNOPSIS
[modified]m42/test/test_download.py: Get all download info from a config file.
[modified]m42/test/yaml.conf: Config file specified download cache location.

DETAILS
This is a step towards removing hard coded URLs from the test code,
as this makes runnig tests in various environments difficult.
download.py now reads yaml.conf to get the parameters of the
test and uses those parameters to run the tests.