First stab at filling out installation info

I tried to write information explaining the development process for someone new to python and its packaging.

I haven't filled out all sections yet. I would appreciate hearing feedback on how adequately you feel the **What tools to use** section covers the points mentioned in ``FIXME``.

The section I added, **Goals and Workflow**, which described the reasoning behind the common workflow of using pip+virtualenv to develop python projects as a developer, might somewhat collide the **What tools to use** section. I'm not sure whether they might be better being merged in any way, and if so how.