Convert pip build.sh scripts to setup.py

[jeanconn]

See discussion in #19

[jeanconn]

It will probably be worth digging in a bit to see how the installs differ. Also see #18 for more discussion.

[jeanconn]

Looks like we if we stick with pip it should also have "--ignore-installed" in our version. I just ran into the issue where apparently pip it wouldn't let me make a conda package of Python module at a version because that package was installed in my environment at that version. Unlikely overall but annoying. (Actually, that just looks to be another bug in process or recipe, as I should be building in a naked environment so this should never happen)

[taldcroft]

At some point we will be maintaining only Py3 versions of our namespace packages, at which point we can use native namespace packages. At that point we don't need --egg for those, FWIW. Or we can just use setup.py install --single-version-externally-managed.

[javierggt]

This was one of the first things fixed in shiny, right?