tox: add {posargs} option to test environments

This allows us to inject py.test arguments to tox in the following way:

`tox -e py27,py33 -- --collect-only -v`
Fix system.map handling in multiple places

This fixes the handling of the system.map file (job description) in
several places: project creation, deployment, and execution. It was
completely broken, evidently by
d0325d7ac043a0a3ae62541ec78daccc9cce66ab.
Merge pull request #165 from larsbutler/fix-system-map-handling

Fix system.map handling