Created a Boost.Python module interface in libcalamares.
Added a PythonJob wrapper and exposed it in the Python module.
Rename target calamareslib ==> calamares so in Python it's libcalamares.
Python-related classes in libcalamares that aren't exported as C++
symbols are now in a CalamaresPrivate namespace.
Import the libcalamares python module into every Python script before
running it.
Added Python error handling to PythonJobHelper.
Added some more testing code to dummypython module.
