elpy-project-root: New function to find and return a project root.

The old method used to just look for .ropeproject. The new method
is a lot smarter. This is used by Rope only for now, but we'll add
other packages that will require a project root.
find-file-in-project: New dependency.

elpy now uses find-file-in-project to quickly navigate to files
in your project. This uses the existing elpy project root functionality.
idomenu: New dependency.

idomenu uses ido to complete imenu entries. Very handy.
nose support: Run tests using nosetests.

This integrates testing with elpy.

Closes #18
Startup: require flymake

This is required for elpy-clean-modeline to work correctly.
elpy-occur-definitions: New function, bound to C-c C-o

The function shows an outline of the definitions in the current buffer,
allowing the user to get an overview of the current buffer and jump
to the definitions quickly.