New plugin to install python packages with pip
Add missing override for the on_remove_node method
Documentation for the pypackage plugin
raise NotImplementedError in on_remove_node callback
Wording fixes
Renaming pypackage to pypkginstaller - part 1
More renaming
Missing sample output line
plugins: pyflakes clean-up on PyPkgInstaller
Merge branch 'pypkginstaller-plugin' into develop

closes gh-224
plugins: update __all__ with latest plugin modules