[#1409] Signal changes in log configuration.

Problem description
===================

When changing the log options, we want to reconfigure the logger,


Changes description
===================

Add signal notification for file, file_rotate_*, syslog and windows_eventlog

Add changes listeners for file, file_rotate_*. syslog and windows_eventlog. When settings are changes, the logger will automatically try to reconfigure.

The tests were cleaned so that all _Logger related tests are inside TestLogger suite, and Handler specific tests are in separate suites.

`TestLoggerWindowsEventLog` was removed and merge into the TestLogger.

`TestLoggerHandlers` was renamed to TestLogger

`getAllOpenFileHandlers` was removed since it is no used in any other part and I don't know why we need it.

The notification signal is a post-update, signaling that notification
was already changed.

On failures in subscribed notifications, the value is set to previous value.
This is done in the log_section itself in a magical way.
I am not happy with this, since the log sections should only care about
setting and notifying.
In an ideal world, the subscribers will catch the errors themselves and will
revert the value... the problem is that when subscribers reset the value,
they will trigger another round of notifications...harry stuff.

The log reconfiguration of the logger happens in the background in the
chevah.utils library.. and server has no idea about what is happening there.
I have a separate branch to inform the server when chevah.utils.logger is
doing changes.

Also changes for file, file_rotate_external, file_rotate_count ... etc are not aggregated and each change will trigger a different reconfiguration process. This is stupid but I tried to keep the code simple as this branch is already growing to big. The Local Manager should be more inteligent and try to reduce the need for multiple reconfiguration.
If there are problems we can solve them in a separate branch.

setting file_roteate_each to (0, 'anything') will also disable the rotate each logger.


How to try and test the changes
===============================

reviewers @alibotean @bnickname 

Check that changes make sense.

I did a first integration test with the server and the API is good enough.

I am not sure that the changes are 100% what we want, but if this branch is good enough we can extend it in another ticket.