+ uses the changes in the preload method

- found a way to make it implements the socketserver.ForkinTCPServer features reducing the global code size (and removed a lot of dirty copy & paste from cpython sources)
- deleted useless imports

- the reserved context is create and set at init time by the LodelContext.init method
- allows to use lodel libs will loading
- no special features implemented yet

- updated scripts etc
- make tests pass

Method is now disabled in MONOSITE mode

- Replaced some "hidden" import with LodelContext.expose_modules calls
 - in some functions of Setting, Plugin, validator
 - in loader.py (temporary version)

In this state the tests runs (151 success), I'm able to run an instance (from debian package using slim) in MONOSITE mode and in MULTISITE mode by creating and loading a context in the loader.

Test passes

Changed the exposure specs to allow giving an alias for an object when importing using the from x import y,z form

When not found return None and do not try to run len() on None

Return an instance and not a list of len 1 anymore

In construct and check data

with make deb . Next commit will update the README

Before when session restore fails the webui was answering "Unknown status 200" as content.
Now it produce 2 log messages (maybe)

broken nginx conf + absolute path in slim that is known only at build time

Adds a LODEL2LOGDIR to buildconf.py
Adds a nginx-conf option to slim
...

It a real buildtime variable, the localestatedir

SLIM is now able to edit configuration from CLI, to start instances etc.

when a value is composed only with space tabs etc consider it as None

- Written a new custom_list validator, it takes another validator name as argument (in order to validate items of list)
- Using it to validate list of plugins names

Implements the check of the bases classes of a datasource class in a datasource plugin ( solves #144 )

refs #132