Configure system to use unmodified environments

[nottombrown]

In order to compare performance with existing baselines, we should have the default use exactly the same environment semantics as the standard gym env

e.g. the following should match the normal Reacher-v1 behavior

python rl_teacher/teach.py -p rl -e Reacher-v1

If you want to use modified envs you can use ReacherNoTorque-v1 and ReacherNoTorqueFixedLength-v1