test suite

[Alexandre Detiste]

I updated the wiki dating from 2011:
  https://wiki.debian.org/Games/GameDataPackager

I retained & reworded the idea of a test suite.

In my tree I've modified "def choose_mirror(self, wanted):" to make
it prepend the content of MIRROR to the mirror list;
a test suite would just "export MIRROR=localhost" and try
to package every demo.

Alexandre