Update README.rst for instructions on running from python
Update README.rst for instructions on running from python

* Added the subset of the CLI options when running pylama from python. CLI options like report, abspath and format cannot be used.

* Added the rootdir parameter to check_path() call. Without this parameter, the python code is unable to get the relative paths of files to be audited and results in the following error.

    "[Errno 2] No such file or directory: '<filepath>.py' [undefined]"

klen/pylama