Deprecate Use of imp in Favor of importlib on Python >= 3.1

The imp module is deprecated in favor of importlib as of Python 3.4 … should update Cement (with backward compat for imp on Python < 3.1).

[grbd]

Hi, I recently stumbled across this issue when googling for a solution for another project with a similar problem. I managed to figure a way of importing by looking at the code for importlib

# New way of importing
def path_import2(absolute_path):
   spec = importlib.util.spec_from_file_location(absolute_path, absolute_path)
   module = spec.loader.load_module(spec.name)
   return module

# Original way of importing
def path_import1(absolute_path):
   '''implementation taken from https://docs.python.org/3/library/importlib.html#importing-a-source-file-directly'''
   spec = importlib.util.spec_from_file_location(absolute_path, absolute_path)
   module = importlib.util.module_from_spec(spec)
   spec.loader.exec_module(module)
   return module

[derks]

The imp module will be removed in Python 3.12, moving this to Cement 3.2 dev.