Remove explicit depend on distribute.

Things in the world are moving towards setuptools 0.7, and
there is not a path between distribute and setuptools. Our explicit
dependency on setuptools is causing us to have to write patches to
try to jump through additional hoops to get it to install in the
right contexts.

Fixes bug 1189941

Change-Id: Id7a749c02203100dab52160a551d3548c8a48fd6