Fix package_dir to properly reference lib. Remove extraneous include.

This pull request fixes some of the package details in setup.py and allows for ansible to be installed in develop mode (a.k.a. `pip install -e https://github.com/ansible/ansible.git`).

It fixes #558 (which was closed pending a proposed fix, which this pull request is).

The problem boiled down to a slightly incorrect construction of the `package_dir` argument to `setup()`.

Proper usage of this setting is described [here in the disutils docs](http://docs.python.org/2/distutils/setupscript.html#listing-whole-packages). Those docs actually perfectly describe the ansible set up, where source code lives under a `lib` subdirectory. They suggest using `{ '': 'lib' }` and then explicitly listing out the packages that live there. This is what my pull request accomplishes.

That's the easy explanation, and if you read those docs I linked to above my change aligns with the recommendation there.

The more confusing bit is the fact that this *should* apparently play nicely with `pip install -e` / `python setup.py develop` as it is written now. Why it doesn't play nicely is apparently an issue that the distribute folks are contending with, see here: https://bitbucket.org/tarek/distribute/issue/177/setuppy-develop-doesnt-support-package_dir

In short, this change should not alter behavior for normal `python setup.py install` usage but should allow developers to install in editable mode via pip if they choose to.

(The change to MANIFEST.in removes an include that references a non existent file and throws a warning during pip install process.)