Revert "travis-ci: force pylint testing against the installed module"

At some point we probably won't install all the files that we want to
run lint against, e.g. all testing code may not be installed in the
future.
convert NEWS and README into rst files

This allows use to use the github renderer to show a better README file
by default and deprecate/drop the usage of the custom txt -> rst news
generation method for building the docs.