Implement config override via GUMBY_* env variables.
Implement variable expansion in scenario scripts.
Fix and improve the env. build script
New set of R scripts imported from the legacy tree

* legacy_experiments/scripts/r/test_bootstrap.r:
Working experiment with allchannel scenario, still lots of stuff to
refactor on the client code.
First iteration at base class for dispersy based experiment nodes
Start counting from 1 to keep backward compatibility with legacy
imported scenarios.
Do not try to stop the reactor several times.
Clean and compile pyc too.
Export R_USER_LIBS variable too.
Compute and store the jiffie to seconds ratio and store it on the header
of the resource usage log.
Oops, wrong indentation.
Enable resource usage monitoring.
Be less verbose when copying the data back.
Add a new remote_workspace_dir config option so we can specify where the
experiment dirs should be created on the remotes.
Do not silently ignore unknown/non-registered actions.
Use the new remote_workspace_dir config option
Be less verbose when rsyncing data and delete the redundant output/ dir.
Import the reactor later to allow the EPOLL based one to be installed.
Logger config file for the dummy experiment collection