Plugin organization

[tasleson]

Move the python plugins out of lsm.plugin.

~First step in resolving: https://github.com/libstorage/libstoragemgmt/issues/440~ Fully addresses https://github.com/libstorage/libstoragemgmt/issues/440

Passes make check & make rpm

Notes:

• Plugins written in python are now located in their own directory
• Python modules & plugins which contain compiled C extensions are located in %{python3_sitearch}
• Removed separate packages for the C extensions, they are now bundled with python code that cannot function without them
• Spec. file is used for testing, but is not used in official Fedora/EL repos. Changes made here will get propagated to them with the next release