Python modules as individual resources

This patch replaces the script using pip to install needed python modules with the python_pip LWRP.  The directory and git resource that are run at compile time are so we have the requirements.txt file to parse and create pip resources for.  I also rearranged the order for readability putting together things done at compile time (the git and directory resources as well as the data gathering and requirements.txt parsing) followed by resources that are converged normally.