Feature/find+python+module

(From previous commit:)
    Added modules for finding Python libraries.
    
    FindPythonModule.cmake offers the find_python_module() function,
    which acts similarly to the simple invocation form of
    find_package().
    
    FindPythonCython and FindPythonNose are two specific cmake
    scripts that use FindPythonModule to check for the presence
    of their respetive packages.

As I started fixing this up (there are some major bugs, it turns out, that I had inadvertently left in FindPythonModule), I did encounter a problem: the convention is that to FindFOO has FOO in camel case or uppercase, but find_python_module requires the case-sensitive name of the python module (e.g. 'Cython' or 'nose'.)

Either we have:
1. an implicit convention that transforms python case-sensitive module names (possibly with underscore) into camel-case names. e.g. 'Cython' -> 'Cython'; 'nose' -> 'Nose'; 'piston_mini_client' -> 'PistonMiniClient' (for example), or
2. each FindPythonFOO.cmake script understands the relation between the camel-case or uppercase name FOO and the case-sensitive python module name 'Foo' or 'foo', and tells find_python_module in some fashion weather to perform QUIET or REQUIRED behaviour accordingly.