core: twistd plugin refactoring:

initialisation method manage things which must be done once (reactor installation + logging configuration), this method is called when service is created, so we can have the options passed to twistd (necessary to manage logging configuration). The initialisation order is important: for instance, sat_main must be imported after logging initialisation.
This refactoring avoid initialisation issue when SàT backend and libervia are both installed as twisted plugins.

src/core/sat_main.py

@@ -19,8 +19,6 @@
 
 from sat.core.i18n import _, D_, languageSwitch
 from twisted.application import service
-from twisted.internet import glib2reactor
-glib2reactor.install()
 from twisted.internet import defer
 from twisted.words.protocols.jabber import jid
 from twisted.words.xish import domish

src/twisted/plugins/sat_plugin.py

@@ -35,14 +35,18 @@ from twisted.application.service import IServiceMaker
 
 # XXX: We need to configure logs before any log method is used, so here is the best place.
 from sat.core.constants import Const as C
-from sat.core import log_config
-log_config.satConfigure(C.LOG_BACKEND_TWISTED)
-
-# XXX: SAT must be imported after log configuration, because it write stuff to logs
-from sat.core.sat_main import SAT
 from sat.core.i18n import _
 
 
+def initialise(options):
+    """Method to initialise global modules"""
+    from twisted.internet import glib2reactor
+    glib2reactor.install()
+    # XXX: We need to configure logs before any log method is used, so here is the best place.
+    from sat.core import log_config
+    log_config.satConfigure(C.LOG_BACKEND_TWISTED, C, backend_data=options)
+
+
 class Options(usage.Options):
     optParameters = []
 
@@ -55,6 +59,9 @@ class SatMaker(object):
     options = Options
 
     def makeService(self, options):
+        # XXX: SAT must be imported after log configuration, because it write stuff to logs
+        initialise(options.parent)
+        from sat.core.sat_main import SAT
         return SAT()