Execute experiment in different environment

Currently, when executing an experiment on a local machine, the current environment is used and therefor must contain all the packages needed.

This is sub-optimal as several different experiences might required different sets of packages.

While this can't be done with the local executor, it can be implemented using the subprocess executor.

The subprocess executor makes call to the scripts needed to run the algorithms/databases processes as would be with the docker executor. This fact can be used to run the scripts from another environment and thus will use the packages available there.

This will also simplify the creation of new execution environment and their transition do docker images.