Bumping up version number and updating docs in prep for release (py-w…

…hy#143)

* added cate estimator to causal estimator and one specific estiamtor for linear regression

* Started with a better error message for estimators that do not support CATE as yet, but then generalized to add error messages for when any specific method is not implemented for an estimator.

* added docstrings for the new functionality

* added a warning if effect modifiers provided are extra from the ones specified before, and fixed a bug for discrete variables

* updated files in prep for release of v0.4

updated version number to 0.2

commits to publish to pypi

Update README.rst