BACKPORT to Python-2 compatible!!!

* core: Experiment accepta a single model.
* tests: seems to fixed misterious transplant tests (but still differ
from older results).
* docs: Minor improve python-install instructions.
* docs: README: python-2 compatible
* deps: Do not require high matplotlib, not wildly avail yet.
* tools: Rework sed tool for cleaning-up restructured, uploaded into:
http://stackoverflow.com/questions/16367770/my-rst-readme-is-not-formatted-on-pypi-python-org

ALL TCs OK for py-2.7 & 3.3
DOCTESTS FAIL in 2.7 (disabled in TravisCI)