BF: Ensure all imports for fail2ban modules are not relative
ENH: Python based actions

Python actions are imported from action.d config folder, which have .py
file extension. This imports and creates an instance of the Action class
(Action can be a variable that points to a class of another name).
fail2ban.server.action.ActionBase is a base class which can be inherited
from or as a minimum has a subclass hook which is used to ensure any
imported actions implements the methods required.
All calls to the execAction are also wrapped in a try except such that
any errors won't cripple the jail.
Action is renamed CommandAction, to clearly distinguish it from other
actions.

Include is an example smtp.py python action for sending emails via smtp.
This is work in progress, as looking to add the <matches> and whois
elements, and also SSL/TLS support.
ENH: Add matches to smtp.py action
ENH: python actions use initOpts as **kwargs

Adds an easy way to handle case where mandatory arguments are missed, or
not valid arguments are passed
TST: Add non-callable values to CallableMap test
BF: Incorrect number of arguments in smtp.py action connect log
BF: Stop actName being passed to python actions
RF: Refactor actions further, include removing server proxy interface

This allows direct setting of action properties and calling of methods
from the fail2ban-client if so required.
TST: Fix sorting of properties and methods in servertestcase in python3
ENH: Change all imports to "." style relative imports
RF: Change Jails and Actions to Mapping types
DOC: Update docstrings in action
DOC: Update docstrings for smtp.py action
TST: Added some more tests for Python actions
Merge pull request #549 from kwirk/python-actions

ENH: Python actions