support both setuptools and distutils installation methods for easyconfigs
add robot path and distutils easyconfigs install path (install prefix) to list of paths considered
add robot path to list of paths searched for patch files, use get_paths_for to determine easyconfigs install path
use __file__ to refer to set of provided test modules, so unit test suite can be run outside of framework source dir
fix long line
fix searching for patches in robot and installed easyconfigs dirs, also include alternative directories searched
Merge pull request #433 from boegel/easyconfigs_install_path

fix default robot path for distutils installation, also search robot path for patch files